v2.0.4

The most important fix in this release is that we no longer log errors inside the signal handler in loop_poll.c
This could cause an application hang in some circumstances.

Chrissie Caulfield (3):
doxygen2man: print structure descriptions (#443)
Fix pthread returns (#444)
poll: Don't log in a signal handler (#447)

Christine Caulfield (1):
Bump library version for v2.0.4

Jan Friesse (1):
Implement heap based timer list (#439)

orbea (1):
build: Fix undefined pthread reference. (#440)