Fixed the issue with newly built application not opening under OS X (closes #347).

The previous ‘fix’ was always starting OpenCOR in GUI mode (!!).
Some work towards upgrading to LLVM 3.4.1 (#349) [ci skip].
Some minor cleaning up [ci skip].
Some minor cleaning up [ci skip].
Some work towards upgrading to LLVM 3.4.1 (#349) [ci skip].
Done with upgrading to LLVM 3.4.1 (#349).
Some work towards writing some sample plugins (#337) [ci skip].
Some minor cleaning up [ci skip].
Fixed the issue with anchors not working with our fixed header (closes #350) [ci skip].
Fixed the issue with anchors not working with our fixed header (closes #350) [ci skip].
Some minor cleaning up [ci skip].
Some minor cleaning up [ci skip].
Some work towards writing some sample plugins (#337).
Some work towards writing some sample plugins (#337).
Some minor cleaning up [ci skip].
Some work towards writing some sample plugins (#337).
Some work towards writing some sample plugins (#337) [ci skip].