Now possible to RELEASE a single channel

[Rias]

Per the changelog: It is now possible to specify a particular channel with the release command in order to drop only one specific channel. Example: release geomancy (can be abbreviated). In the case of multiple active channels of the same type (such as sorcery), specifying will release only a single channel of that type.

This should make rotating through those multi-element weaves much more viable, as well as utilizing multi-channel sorcery casts now that it's not necessary to drop all channels at once and start a new channel in order to drop back down from a single powerful cast.