Merge pull request #91 from Gaerzi/master

Sync with my fork.
Merge pull request #92 from Gaerzi/master

Sync with my fork.
Merge pull request #93 from Gaerzi/master

Sync with my fork.
Fix res folder detection in linux (case-sensitivity)
Update CMakeLists.txt so that it shows less errors on configuring
Merge branch 'master' of https://github.com/sirjuddington/SLADE