fresh copy of repository for proto v4 development

[SVN r44395]
proto v4

[SVN r44402]
eliminate need for child_traits, handle function references as terminals correctly

[SVN r44563]
clean-up in skip_primitives

[SVN r44565]
don't double-deref args to make_expr, nuke trailing spaces

[SVN r44677]
merged from trunk

[SVN r45844]
merged from trunk

[SVN r46061]
merged from trunk

[SVN r47983]
merged from trunk

[SVN r48076]
merged from trunk

[SVN r48080]
merged from trunk

[SVN r48169]
merged from trunk

[SVN r48673]
merged from trunk

[SVN r49133]
merged from trunk

[SVN r49439]
merged from trunk

[SVN r49607]