* libguile/eval.c (s_mixed_body_forms): New static identifier.

	* libguile/eval.c (s_mixed_body_forms): New static identifier.

	(canonicalize_define, scm_m_define): The check for a bad
	expression is performed in canonicalize_define now.

	(try_macro_lookup, expand_user_macros, is_system_macro_p): New
	static helper functions for m_expand_body.

	(m_expand_body): Use ASSERT_SYNTAX to signal syntax errors.  Only
	expand user defined macros.  Fixed handling of the definition/
	expression boundary.  Fixed handling of definitions grouped with
	'begin.  Use canonicalize_define to expand definitions.

	* test-suite/tests/syntax.test: Tests that check for the correct
	handling of internal defines with begin work now.