* Add info/link for the postgreSQL wrapper

It turns out that all changes should go into the main repository, see https://github.com/hunter-packages/IF97/pull/1

* Structured the processing of CMake options
* Cleaned CMake command spelling
* Added the version number to CMake
* Fixed the CMake command in the docs
* Added a link to the wrapper README

* added algorithm include 
* bumped version number
* turned build switches into options
* added a standard interface library target IF97_CMAKE_MODULE
* minor adjustment in documentation

* Added Travis configuration based on the CoolProp settings
* Enables Travis CI for the master branch
* Coverity scan is limited to the coverity_scan branch

Revert emplace_back to the non-C++11 push_back

* Update CMakeLists.txt to Build Wrappers

  - Build for either Mathcad 15 or Mathcad Prime 3.x
  - Slight mod to IF97.cpp for WIN32 builds
  - Updated README with Build instructions

* Included Mathad wrapper header files in VS project via CMake script

* Fix memory allocation for Mathcad if97_getvers() function, which returns a string

* Added utility routines for forward and reverse vapor quality

  - Calc vapor quality within vapor dome
  - Calc H, S, U, V in terms of P & Q
  - Update documentation
  - Minor fixups with CMake script
  - Minor fixes to eliminate compiler warnings
  - Updated version to 2.1.0

* Patch RegionOutput(key,T,p,SatState) for results on saturation curve.

* Add error code in Mathcad wrapper for catching UNKNOWN exceptions.

* Catch IF97 exception in Mathcad wrapper when (T,p) state lies exactly on saturation curve.

* Clarify branch conditionals with {}

* Patch rho_pX() function in IF97.h

* Added Mathcad wrapper functions for rhoph and rhops for testing of rho_pX function.

* Added Mathcad stub routines for rhoph and rhops.

2) fix in "inline double rho_pX" function
3) replaced pow(somethig, 0,5) with sqrt
4) replaced pow(somethig, 2) with something*something
5) std::vector::push_back replaced with reserve + emplace_back
6) some approaches to vectorize calculations in Region5::T_p(double p)
7) added const modifier in constant methods
8) some little optimizations

* Added optional compiler switch to use IAPWS Release Doc units if so desired - [MPa] & [kJ].

* Leave surface tension in [N/m] (kg/s-s) units in all cases

* Modify verification program IF97.cpp to use IAPWS_UNITS switch

* Minor edits to IF97 README for compiler switches

* Final mods for version 2.0.0

 - fix-ups for integration into CoolProp
 - Additional Comments
 - Added functions for Prandtl Number
 - Added Prandtl Number functions to standalone Mathcad wrapper
 - Updated Mathcad wrapper verification files

* Provided a get_if97_version function and updated documentation

* Added IAPWS Viscosity functions using Industrial Formulation recommendation.

* Added Mathcad verification document so changes can be tracked and used by others.

* Added Viscosity functions to Mathcad wrapper function doc.

* Added IAPWS surface tension function in Region 4 along saturation curve.

* Added surface tension function to IF97.h
* Added Mathcad wrapper function "sigma(T)"
* Updated Mathcad wrapper verification sheet and PDF
* Updated Mathcad wrapper function documentation

* Move Viscosity equations to base region

* Abandoned idea of a "Region 0"
* Put viscosity equations into base region
* Added dRho/dp function in preparation for Thermal Conductivity

* Added Specific heat equations from IAPWS 2011 Revised Release

* Specific heat equations added
* Mathcad functions implemented
* Mathcad function documentation updated
* Verification Mathcad and PDF docs updated

* Updated REAMDE.md to reflect addition of Transport Functions

* Override critical enhancement of thermal conductivity in Region 5 to 0.0

* Minor comment and enumeration fixups.

* Implementation of Backwards Equations p(h,s) and T(h,s).

* Spell checked comments in IF97.h and new Mathcad code stubs.

* Fixed typos in README file.

* Add Reverse Equations for T(p,h) & T(p,s)

* Update the IF97.cpp verification program for reverse functions.

* Updated README files for Backward Functions.

* Updated README files for Backward Functions.

* Fixed Typos in IF97.cpp verification code and README.md

Add trivial parameters as constants to IF97 namespace.

Fixes warning: Addresses CoolProp Issue #1277

Fixes warning: potential to reach end of non-void function without a return value (in SatSubRegionAdjust)

Saturation Functions

I combined everything into parametric calls to RegionOutput with a new
enumeration for saturation state (IF97SatState).  This cleans things up
immensely and removes the need for the extra SAT/VAP enumerations in the
IF97parameters list.

I left the API functions separate as this keeps the interface as clean
as possible and consistent with the original six base property functions
(they don't take an enumerated property parameter either, so there are
six separate functions).  Any calling routine does not need to know
about the enumerations; just provide pressure for a given property call.
The function names follow a standard convention and everything goes
through a call to RegionOutput().

I also moved "region" out of the parameter list for RegionOutput(),
since I think it will ALWAYS be provided a call to
RegionDetermination(T,p).   I don't think there would ever be a reason
to force region equations to extrapolate outside of their intended range
(e.g. calling RegionOutput( REGION_X, T, p, NONE) for a region not
determined by T & p).

Fixed typo of SatSubRegionAdjust() in both definition and call.

Less disruption to Region 3 output function from original.

Added two new boolean functions to make the saturated liquid/vapor logic
independent of the order of the I97 enumerations.  Logic tested and
verified on the Mathcad verification sheet.