Merge pull request #85 from gambiteer/master

Update gcc to latest version, enable Graphite loop optimizations
Universal backend: add representation of procedures as classes
Merge branch 'master' of https://github.com/feeley/gambit
Universal backend: implement simple separate compilation
Change gsc command line processing to allow target specific options.
Universal backend: add u16vectors
Make numeric type dispatch more portable (and probably slightly more efficient)
Add primitives to construct and access ratnums and cpxnums
Universal backend: add more numerical types and f64vectors
Universal backend: add compiler command line options to select representation of Scheme objects
Universal backend: fix identifier generation problem
Universal backend: add selftests for various Scheme object representations
Universal backend: better support for procedure representation as class
Universal backend: support all the procedure representations on all targets
Universal backend: support class representation for fixnums
Universal backend: comment out unit testing for PHP 5.2
Universal backend: optimize unboxing of boxed literals
Universal backend: add primitives for bignum support
Allow user interrupt during ##wait-for-io!
Get rid of "Interrupted system call" on output-port-width when generating output in the background