Fix SCons bugs

Don't clober the Environment (and thus the ENV['PATH'] by redefining it
and don't link against lr by default. Only add it if uname is not Darwin
Clean up ENV

Don't pass the entire environment to SCons. Only pass the PATH
Merge pull request #46 from jrozner/master

Fix SCons bugs
Ditch longs and long longs in favor of stdint.h types, which has cascading
effects throughout, including use of inttypes.h/PRI[ud]64 because printf() is
still stuck in a long world, conversion of %lu to %zu for printing values of
type size_t, and changing/renaming the g_check_cmp* family of functions.
Merge pull request #48 from pete-/master

Ditch longs and long longs in favor of stdint.h types, which has cascadi...
Add internal conditional to not use stdarg.h for SWIG use
Merge pull request #50 from thequux/conditional-varargs-in-header

Add internal conditional to not use stdarg.h for SWIG use