hgweb: if the server supports it, send a compressed bundle

Use httpconnection even with proxies. This should give us HTTP keepalive when we talk to proxies and should allow us to stream a file in unbundle (instead of reading everything into a string). This should fix issue376.

issue352: disallow '\n' and '\r' in filenames (dirstate and manifest)

hgweb: split URLs containing spaces or other escaped characters correctly

zsh: perform ~ expansion on _hg_root

mq: handle qpush -a with empty series

zsh: compute repository root instead of forking hg

zsh: complete users in ssh URLS

zsh: support remote cloning

zsh: add optional remote directory cache