Moved terms implementations to .cc files.
Moved term_walker_t implementation to term_walker.cc.
Removed unused types broken_client_exc_t and bad_query_exc_t.
Removed unused meta_check function.
Got rid of rdb_protocol/pretty_print.hpp.
Merge branch 'next' into sam_etc_deheaderize

Conflicts:
	src/rdb_protocol/term_walker.hpp
Moved transform_visitors.hpp implementations to cc file.
Merge branch 'next' into sam_etc_deheaderize
Merge branch 'next' into sam_etc_deheaderize

Conflicts:
	src/rdb_protocol/terms/rewrites.hpp
	src/rdb_protocol/terms/seq.hpp
Renamed fill_in_backtraces to preprocess_term.
Renamed propagate_backtraces to propagate_backtrace.
Moved rdb_protocol/terms/... headers to terms.hpp.
Merge branch 'sam_etc_deheaderize' of github.com:rethinkdb/rethinkdb into sam_etc_deheaderize
Merge branch 'next' into sam_etc_deheaderize