Move record declarations to .hrl file.
Improve types and format.

Changed records to a .htl file.
Improved types in lhttpc.erl and lhttpc_manager.erl
Improve types and format in httpc_lib and httpc_sock.

Still need to to the same with lhttpc_client.
Improve doc and specs in lhttpc_client module.

Added specs for some of the functions.