Changes

Added Guild# getTextChannelById, getTextChannelsByName,
getVoiceChannelById, getVoiceChannelsByName, getRolesByName Reordered
the listing of methods in Guild in-line with new mentality of Single
object methods first, List methods second.
 (commit: a1af0d3)

First pass on the Call system. Incomplete, but should maintain the cache
for the most part. Fixed cache issues related to removal of
relationships. Made EntityBuilder#createMessage update fake user info
correct. Create GuildVoiceState and CallVoiceState. Will implement
acquring in-process calls on startup later. Needs many events, will
implement later.
 (commit: 012cf6b)