Add new setting value prompt_overrideSvnStatusOptIn to cmder_prompt_config.lua.default to control of asynchronous svn status update should be used with clink
The Cmder prompt normally includes version control info, which involves
running some potentially expensive commands. The cmder-powerline-prompt
project (and maybe other projects) replaces the Cmder prompt and runs
the same potentially expensive commands -- so expensive commands get run
twice!
This change makes it possible for the user and/or other scripts to
disable the version control part of the built-in Cmder prompt.
https://github.com/chrisant996/cmder-powerline-prompt
Setting `prompt_overrideGitStatusOptIn = true` will override the
`cmder.status` and `cmder.cmdstatus` git config settings and run the git
prompt status commands in the background. But it only takes effect when
using Clink v1.2.10, since that's required in order to run prompt update
commands in the background.
