Make some functions static

They're only used within specific source files, so they might as well be
static.
Rename internal function

Want callbacks to end with _cb.
Upgrade fuq.h to v1.2.2
Add few more things to gitignore
Improve performance on loop_block()

Currently loop_block() calls async_send() every time. Instead add a
queue for all threads that need to block and check if it's empty just
before entering idle.