add lwt-log lib (unix free) rev1
better interface for Lwt_log_rules

better interface for Lwt_log_rules
update doc wrt previous changes
typo
restore type equality
move type equality close to corresponding doc
add lwt.log to apiref-intro
Revert "move type equality close to corresponding doc"

This reverts commit b696a017fece523e503f3f7dff3dd6dcb7134ce7.
better doc for Lwt_log
Merge pull request #5 from besport/lwt-log

add lwt-log lib (unix free)