strip trailing whitespaces
Makefile tweaks

added compilation of example.c.
treat compilation warnings as errors.
ssw_test depends on kseq.h too.
Added compilation of C++ version and example.
Fixed compilation warnings in ssw_cpp.cpp

ssw_cpp.cpp: In function ‘int {anonymous}::CalculateNumberMismatch(StripedSmithWaterman::Alignment*, const int8_t*, const int8_t*)’:
ssw_cpp.cpp:156:15: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]
ssw_cpp.cpp:183:22: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]
ssw_cpp.cpp:189:22: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]