WIXFEAT:4378

Add WixBundleOriginalSourceFolder variable (WixBundleOriginalSource
minus file name).
Add WixBundleOriginalSourceFolder documentation
WIXFEAT:2742

Add ProcessorArchitecture Burn variable.
Merge pull request #35 from barnson/develop

WIXBUG:4418
Merge pull request #36 from barnson/wixfeat_4378

Conflicts:
	History.md
	src/burn/engine/cache.cpp
Merge pull request #37 from barnson/wixfeat_2742

Conflicts:
	History.md
Add ProcessorArchitecture to variable list.
Merge pull request #39 from barnson/wixfeat_2742

Add ProcessorArchitecture to variable list.
WIXBUG:4434

Assert maximum patch baseline id length (because of MSI limitation in
transform substorage ids).