docs: update evolve-faq.rst with new prune flag and proper vocabulary Also strip trailing newlines.

prune: spell --successor flag without any unnecessary shortcuts If a user wants to spell out -s, it makes sense to allow that. Before this patch, prune would complain that --successor is not a recognized option. Obviously people don't usually need to spell --successors by hand thanks to shell completion (at least for Bash) using debugcomplete to see all available flags, so this patch doesn't bring any need for more typing. And thanks to Mercurial understanding shortened forms of command-line flags as long as they are unambiguous, the old-style `--succ` flags still work normally, and there are tests that use them. But two tests now use the full form to demonstrate that both ways work.

py3: redefine "troublecategories" in evolve as a dict We'll want to the keys to be bytes and the values to be unicode on py3. Having it defined as a dict makes that easier (instead of converting between the types with e.g. pycompat.sysbytes()). It was kind of ugly to convert between the forms by stripping '_' from the string anyway.

py3: store to __doc__ as str (unicode on py3)

py3: also catch ImportError when relative import fails Python 3 apparently raises an ImportError where Python 2 raised a ValueError.

py3: convert exceptions to bytes using pycompat.bytestr()

py3: use "%d" for formatting integers

py3: avoid "%s" for formatting None

py3: use "%f" for formatting floating point number

py3: fix progress() functions to not use "%s" with int Python3 doesn't support "%s" with int arguments (and not with None arguments either, which this code was also using).

py3: make random topic name generation consistent across py2/py3 random.choice() (and others based on random.randint()) changed between py2 and py3 without a way to get the py2 behavior. However, random.random() did not change, so we can re-implement random.choice() based on that.

py3: convert str to bytes before passing to core exception

py3: convert opts keys to bytes before passing to core APIs

evolve: further clarify when update is performed

py3: avoid comparing int and None