port capitalize_redirects.py to core - done by compat2core script

with some improvements:

- CapitalizeBot extends pywikibot.Bot with built-in 'always' option

- use core-like page.save

- remove obsolete script name from showHelp

- bugfix: call handleArgs before GeneratorFactory
  as in I134529f3a914225d3473b95ca771cf7e7be01a36

- bugfix: show documentation correctly if no generator is provided

- make localized strings depend on the actual working site

bug: 64837
Change-Id: I3f1472808774cb345c617d006ef77d8228680857
Merge "port capitalize_redirects.py to core - done by compat2core script"