revlog: stop exporting node.short

patch: fast-path git case in selectfile() We avoid a lot of complicated heuristics in git cases, where these heurestics may even be broken when copies are involved.

patch: unify backend file access interface - Rename readlines() into getfile(), return data and mode - Make setfile() write a data buffer instead of lines, make mode mandatory.

patch: merge backend setmode() into writelines() Copy handling will be easier to handle in a single method.

patch: stop modifying gitpatch objects gitpatch objects emitted by iterhunks() were referencing file paths unmodified from the input patch. _applydif() made them usable by modifying the gitpatch objects in-place with specified path strip level. The same modified objects were then reused by iterhunks() generator. _applydiff() now copies and update the paths which completely decouples both routines. As a side effect, the "git" event now receives only metadata about copies/renames to perform the necessary copies ahead of time. Other actions are handled in the "file" event.

patch: stop handling hunkless git blocks out of stream Patch changes are emitted by iterhunks() in two separate events: 'file' when hunks have to be applied and 'git' to describe other modifications like copies or mode changes. Note that a file which mode is changed and which content is modified by the same patch will be emitted in both events. It is more convenient to handle all file modifications in a single event. This patch "zips" git actions with regular changes so both kinds can be emitted at the same place.

patch: reindent code