Update cmap resources to use latest versions from GitHub

[dhdaines]

CMap resources are now published via Git, so we can simply include them as a submodule:

https://github.com/adobe-type-tools/cmap-resources

We will still include the necessary files (and the license) in the source distribution, just in case.

This includes some updates as well as two new CMaps (which may or may not be useful).

How Has This Been Tested?

Verified that make cmap still works, and running the standard test suite. Built a source distribution and reran make cmap_clean cmap in it.

Checklist

• I have read CONTRIBUTING.md.
• I have added a concise human-readable description of the change to CHANGELOG.md.
• I have tested that this fix is effective or that this feature works.
• I have added docstrings to newly created methods and classes.
• I have updated the README.md and the readthedocs documentation. Or verified that this is not necessary.