Inconsistencies
Two problems:
1. By convention on iOS, sdk_path should come from titanium.xcconfig.
2. Markdown or markdown2 is included in sdk/module/support. But the path was not being changed before importing them, forcing users to manually install the modules.
I have demonstrated how to fix these two problems in a commit on GitHub. I did not send a pull request, because I have been informed that pull requests are detrimental.
https://github.com/dawsontoth/titanium_mobile/commit/a5d9bf95ba7bcb1f98b9f51964410a7b3376cb89
Mobile Web's build.py does not need a titanium.xcconfig. xcconfig is an xcode thing and is unnecessary for mobileweb. Mobile Web's build.py is loading the markdown files from the "common" folder, which is being added to the system path before importing markdown. On my system, this "common" directory is /Library/Application Support/Titanium/mobilesdk/osx/2.0.0/common.