packaging: process Inno Setup files with Jinja2 I want to make the Inno Setup files dynamically generated. This will enable us to do things like automatically derive the set of files to be packaged instead of having to manually keep lists of files in sync across installers. As the first step towards this, we process the Inno Setup files with Jinja2. As part of this conversion, we had to escape syntax in mercurial.iss that conflicts with Jinja2. I also took the opportunity to include modpath.iss via Jinja2 instead of using Inno's preprocessor. This keeps the Python code a bit simpler. Differential Revision: https://phab.mercurial-scm.org/D7158