Remove Old Manual Linking In Favor Of Autocrossref

* This change only removes brackets (and, in one case, adds two
  brackets). No other changes were made to the dev guide.

* A few terms I missed previously were added to _autocross.yaml.

* Links checked; all internal links link to valid ids except the link
  definitions including "FIXME". (See bottom of the file.)

* A few links were left in where they linked to terms I didn't think
  should be autocrossref'd
Merge remote-tracking branch 'saivann/dev' into finishxref

Conflicts:
	en/developer-guide.md
Merge pull request #64 from harding/finishxref

Finish Implementing Auto Cross-References