Re-added qt library directory to the lib path for linux and mac
Re-added Qt library path for cshell
Unset QT_LIB_DIR for installers

Since we use the one in user's path
Tweaked runtime should be ok now
Some minor fixes

Basically:
1. We expect that for installers user's has Qt in their path
and library path
2. Consistent naming between csh and sh script
Added a comment about future potential error when we will have to build our own Qt
Merge branch 'bug#289_fix_runtime_script'