Catchup merge

Modified ats_specialise_test_drop to handle ats4 test plans

Correct handling of tag name and changeset author in sf-tag-hg-code Addition of sf-push-hg-tags and associated template file, for pushing the tags created in sf-tag-hg-code back out to the MCL. Minor whitespace rationalisation.

Added specification of changeset author when committing. Removed execution of hg out - that's taken care of in the push tags target/template.

Fix: package build fail because there is no package_definitions dir

Introduced new Helium property (sf.spec.ats.version) to specify ATS version

Changed locations of package_definitions to make the files a little bit more usable

Added call to produce package definition peices from system definition(s).

Enabled tool to create arbitrarily deep paths for output

Added a few strategically placed spaces, to improve the indentation of the output.

Merge in tools for manipulating sytem defintions from their own repo.

Move files into a directory appropriate for merging into main config repo.

updated commit message as no longer triggered by change in packages repo

Separate the generation of the system model and the generation of the derived package definition into 2 script so can be run separately