Fix for installation paths with a space in

basename only takes a single parameter.

If $0 refers to a path containing a space (e.g. something in /cygpath/c/Program Files) then it gets interpreted as two parameters and fails.

Wrapping $0 with speech marks means it'll be interpreted as a single parameter, regardless of spaces.
Merge pull request #356 from directhex/master

Fix for installation paths with a space in