* module/language/scheme/expand.scm: New module, implements a separate
expansion phase, not interleaved with compilation.
* module/language/scheme/amatch.scm: Helper for expand.scm, it's pmatch
with support for annotated source.
* module/ice-9/Makefile.am (SOURCES): Add annotate.scm to build list --
early on because it will be used in the compiler.
* module/ice-9/annotate.scm: Fix the printer, default to unstripped
(whatever that is), and add a deannotator.
* module/system/base/compile.scm (call-with-compile-error-catch): Fix for
new representation of source locations.
* module/Makefile.am (SCHEME_LANG_SOURCES): Add amatch and expand.
