Ignore new directories.

Additional directories created for building library to preserve original layout.
Ignore new directories.

Additional directories created for building library to preserve original layout.
Added ROCKETCORE_API to StyleSheet class.

StyleSheet class has public member functions which are now properly exported.
Replaced IN with INCH in Property::Unit enum

IN is already defined on Windows (WinDef.h).
Merge pull request #91 from hoshi10/master

Modify Property::Unit enum and StyleSheet class