Plugin breaks on too-large coqide responses
In some large Coq proofs, responses from the IDE server when using :CoqNext
can exceed 65536 bytes in length, which causes them to be split over multiple callbacks from the perspective of coq-au-vim. This causes the plugin to become unusable for stepping through the proof, since it cannot parse the "partial" XML it receives in each callback (in particular, if a tag is split across two callbacks.)