Fix clang 3.5 compilation

- detect c++11 compatibility at configure time
- only add Warnings if they are supported by the compiler
- cleanup messy Makefile.am
Do not use unix as a variable name

unix is used as a macro name in some headers, avoid it.
Do not redefine the default argument
Comment out functions flagged as unused by clang
Merge pull request #7 from serge-sans-paille/bugfixes/clang-build

Bugfixes/clang build
Merge pull request #8 from dagar/master

cmake
Fixed parser issues - Crash on 'exec'

Signed-off-by: Vinzenz Feenstra <evilissimo@gmail.com>
Make string support for raw strings
Try Except fix && multiple consequent strings should be one
cmake misc cleanup
cmake add clang support