implemented query search and virtual folder (merged from newsearch branch).
match the output header for printing to the message view.
replaced md5.[ch] with public domain code in GNet.
moved mbox.[ch] into libsylph.
moved more modules to libsylph.
moved recv.[ch] to libsylph.
moved html.[ch] to libsylph.
made some core modules library (libsylph).