We recently added the ability to configure copies of the Git wrapper to
launch custom command-lines, configured via plain old Windows resources.
The main user is Git for Windows' `git-bash.exe`, of course. When the
user double-clicks the `git bash` icon, it makes sense to start the Bash
in the user's home directory.
Third-party software, such as TortoiseGit or GitHub for Windows, may
want to start the Git Bash in another directory, though.
Now, when third-party software wants to call Git, they already have to
construct a command-line, and can easily pass a command-line option
`--no-cd` (which this commit introduces), and since that option is not
available when the user double-clicks an icon on the Desktop or in the
Explorer, let's keep the default to switch to the home directory if the
`--no-cd` flag was not passed along.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>