Improve some code comments in the script

Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com>
Add a script to install / update Inno Setup to the mingwGitDevEnv root

Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com>
Make ignore rules non-recursive

Otherwise e.g. Inno Setup binaries would be ignored.

Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com>
Add Inno Setup 5.5.3 Unicode to the repository

Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com>
Use the committed Inno Setup to build the installer

Also support building the installer via wine along the way.

Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com>