store: treat range as a generator instead of a list for py3 compat

ui: add new config option for help text width Before this patch, when printing help text using `hg help`, or `hg log -h`, the output will wrap at 78 chars even if the user has a bigger terminal width and there is no config option to change it, making the experience different from the commonly used `man` tool. This patch introduces a new config option `ui.textwidth`, which replaces the hardcoded number. It's set to 78 by default to maintain compatibility. When set to 0, `hg help` will behave more like `man`.

tests: test histedit base command plan help

largefiles: makes verify batching stat calls to remote Instead of sending stat calls for each files separately, it sends one batch call with stat invocations for all files.

largefiles: change basestore._verifyfile to take list of files to check Makes it easier to use batch stat calls in remotestore to decrease number of round trips.

bookmarks: properly invalidate volatile sets when writing bookmarks This corrects a regression introduced during the 3.7 cycle, but which went undetected due to the surviving-but-deprecated write() method on bmstore.

test-obsolete: update extension in test to actually work This hasn't been testing anything since partway through the 3.7 cycle due to unrelated refactoring. Sadly, the behavior it was trying to prevent reemerged in the codebase at that time. A fix is in the next patch, because proving that the fix was actually correct ended up being trickier than I expected.

bundle2: properly request phases during getbundle getbundle was requesting the "phase" namespace instead of the "phases" namespace, which led to the client still requesting the phases separately after getbundle finished.