Sync \w Github Linguist v7.2.0
Includes new way of handling `heuristics.yml` and
all `./data/*` re-generated using Github Linguist [v7.2.0](https://github.com/github/linguist/releases/tag/v7.2.0)
release tag.
- many new languages
- better vendoring detection
- update doc on update&known issues.
renamed tmpLinguist to repoLinguist and SimpleLinguistTestSuite to EnryTestSuit in common_test.go
changed receiver's name for TestSuites to 's'
fixed comments