Ignore build files in source directory
Fix BS to use python-config

fix: more default python base-names
add: extra python compiler flags
Fixed BS: gfanlib/cddlib checking/building/embedding

fix: cddlib configure checks
add: static building-in
fix: return code for _mod_init functions
Minor fixes + cleanup
Fix config-checks: SING_CHECK_POLYMAKE depends on SING_CHECK_GFANLIB