buildsystem: quoted cmake variables

fixes #4, all variables are now enclosed with double quotes: "${var}"
buildsystem: fixed returning false if list doesn't contain requested item
engine: fixed typo in checking max_texture_units
Merge pull request #92 from TheJJ/cmakequotes

quotes for cmake variables
add -Wno-mismatched-tags flag for llvm builds
Argument '--version'
For writing current version of the Openage
Add myself into authors list
Merge pull request #100 from zuntrax/master

add -Wno-mismatched-tags flag for llvm builds
remove redundancy in buildsystem/cpp.cmake
Merge remote-tracking branch 'zuntrax/master'
Merge branch 'VersionLog' of BugExplorer/openage into master
args: fixed whitespace issues