Merge branch 'jk/config-parsing-cleanup'

Configuration parsing for tar.* configuration variables were
broken. Introduce a new config-keyname parser API to make the
callers much less error prone.

* jk/config-parsing-cleanup:
reflog: use parse_config_key in config callback
help: use parse_config_key for man config
submodule: simplify memory handling in config parsing
submodule: use parse_config_key when parsing config
userdiff: drop parse_driver function
convert some config callbacks to parse_config_key
archive-tar: use parse_config_key when parsing config
config: add helper function for parsing key names

diff --cc builtin/help.c
Simple merge

diff --cc cache.h
Simple merge

diff --cc config.c
Simple merge