Major change of BS

No default hardcoded flags in any makefile.am's anymore in favor of a pair of m4 macro:
SING_RESET_FLAGS sets CXX/CFLAGS = "" if unset, must be called somewhere at the beginning of configure
SING_CHECK_SET_ARGS handles --enable-debug and --disable-optimizationflags (exclusive!) configure arguments, and tests + set multiple compiler/linker flags to CXX/C/LDFLAGS  

SOME NOTES: 
0. --enable-debug and the BS change (above) is mostly irrelevant to omalloc/
1. NDEBUG and OM_NDEBUG has been put into config.h (which should be included by almost all source files)!
2. some compiler flags (-O3?) seem to crash GCC  :( 
3. one can not use -fno-implicit-templates due to heavy template usage in tgc.cc :( 

ps: these changes has been tested extensively via TC and seem to work fine under all our Linuxes.