Issue #75. Makefile detects if included headerfiles have changed.
Sources and more info:
http://gcc.gnu.org/onlinedocs/gcc-4.8.2/gcc/Preprocessor-Options.html
http://www.gnu.org/software/make/manual/html_node/Include.html
http://stackoverflow.com/questions/16221805/why-isnt-make-detecting-changes-in-header-dependencies/16221973#16221973
Merge remote-tracking branch 'upstream/master'
Fixed some lint warnings found by cppcheck.
Fixed lint errors/warnings/style/performance found by cppcheck.
Merge pull request #76 from esper/master

Makefile improvement, cppcheck fixes