Fix incorrect serialization of control characters to \xHH escapes since
JSON only support \uHHHH escapes, and serialization of infinite and NaN
numbers.
Add a variants array which can specify overriden properties of the
info.json for building multiple versions of the mod at the same time and
fix the additonal_files to allow specifying under what path the file is
put.
Together these two changes allow setting up the build to do all
supported versions at the same time and add specialized code for each
version of Factorio supported.
Move the export and clusterio mod code to the slave package and fix the
path used for them. Refactor tests to use temp/tests/ as the cwd when
running integration tests in order to ensure paths to lua code are
correctly handled.
Hornwitser