Adding cos-, sin-, tan- inverse
Merge branch 'Update' of https://github.com/DankSwankwood/CoolCalc into Update

Conflicts:
	CoolCalc2/MainWindow.cs
	CoolCalc2/bin/Debug/CoolCalc2.exe
	CoolCalc2/bin/Debug/CoolCalc2.exe.mdb
	CoolCalc2/gtk-gui/MainWindow.cs
	CoolCalc2/gtk-gui/gui.stetic