Add gemspec

Example file

http://github.com/brianmario/charlock_holmes/blob/dde1946/charlock_holmes.gemspec
Add VHDL syntax highlighting support
Fix WDK compilation.

Close #82.
Merge branch 'mickael9-vhdl'
Merge pull request #80 from svnpenn2/master

Add gemspec
Update Scintilla to 3.4.1 [8164b2].