Don't use the proplists module when decoding error_logger messages

Proplist module is a lot slower than lists:keyfind, which is a BIF,
because proplists has to work with 'bare' atoms as well as 2-tuples.

This should marginally improve the throughput when printing many
error_logger messages.
Add comment and fix EQC generator
Merge pull request #196 from basho/adt-less-proplists

Don't use the proplists module when decoding error_logger messages