pycompat: when setting attrs, ensure we use sysstr The custom module importer was making these bytes, so when we poked values into self.__dict__ we had bytes instead of unicode on py3 and it didn't work.

i18n: make the locale directory name the same string type as the datapath

contributing: add new file with a pointer to the wiki This also includes what I consider to be the minimum set of steps someone should be able to perform even if they can't run the testsuite. Hopefully this will help new contributors know to at least run the two checkers that find most things that (in my experience) require manual cleanup.