New function additions and fixes to the way options are set.

Now library is set as shared instead of static as it should be unless --disable-shared is used. 

The shared|static issue was fixed by adding a function wx.SetOption(name, value) that checks the current configuration been checked and its value in order to properly set each wx option in configure.lua

Added some utility functions to the wx namespace like wx.Execute and wx.unix.CheckLibraryVersion in order to continue moving on.