changed the class Graph name to PropsPlot - more inline with the project
updated PropsPlot.__init__ docstring
added wrapper functions for Ts and Ph plots (backwards compatibility)
added build files to .gitignore file
Merge branch 'python-plots'

Conflicts:
	.gitignore
	CoolProp/gitrevision.h
fixed Ph wrapper docstring examples
moved the PropsPlot.show function to BasePlot
fixed error with None axis being created from Ts and Ph wrappers
added the parsing of the axis instance
fixed error with Ts and Ph wrappers giving empty figures
added drawIsoLines wrapper
added more test plots
return the plotted isolines
Merge branch 'python-plots'
added Ps, PT, Prho, Trho, hs wrapper functions (back compatibility)
Merge branch 'python-plots'

Conflicts:
	CoolProp/gitrevision.h
Merge pull request #20 from lgpage/master

Ts and Ph Wrapper Functions