Ignore return value of lager:dispatch_log in lager.hrl

This is to suppress dialyzer's `unmatched_return` warning

Don't log when we dropped 0 messages

add flush options to proplist validation

Make a few corrections to the recent mailbox flushing changes

Remove code which supports R15

Add custom log rotator option and hourly log rotation

Take a stab at OTP 18 compatability with macro logging

Handle yet another stacktrace form

Sometimes the stacktrace is a larger array of {M, F, A, Prop} tuples.
The handler code was expecting at most 2 tuples in the list. Relax this
requirement and add a test that provokes this edge-case.

support logging with macros per level

Dont flush notify msgs at overload

add reverse_pretty_stacktrace env var, default true

Handle OTP 20 gen_server crash when the client pid is dead

Support unicode format string

A little emphasis on application variable crash_log

Emphasize application variable

Added info about application place holder.

Support for dynamic metadata

Fix the bug with the wrong format.