event_loop_add_fd_watch() and event_loop_remove_fd_watch() now add/remove one type of callback per time.
add header and trailer in each source file

add standard copyright header
add vim hints trailer
Renamed HTTPResponseWriter to HTTPResponse.
Added haders and footers to httpresponse.{c,h}
New HTTPResponse api for buffered I/O.
add the source code decorator script

used in commit ab1f3cdf719fe6e8f7a8bce51edb37fb840cef3d
to decorate the source files.
add usage instructions for cdeco.py
add linking exception; mark the boundary of th API
Merge branch 'feature/buffered-io' into develop

Conflicts:
	src/httpresponsewriter.c
	src/httpresponsewriter.h
	tests/check_httpresponsewriter.c