Update/fix to rust checker.

Switch to --no-trans per https://github.com/mozilla/rust/issues/3808
Switch source to source-inplace since rustc looks for modules in the
source directory.
Add a pattern for rustc warnings and add a unit test.
Update the rust syntax error unit test.
Add syntax checker for GNU Makefile using GNU Make
Merge pull request #314 from capdevc/patch-1

Change rustc invocation to --no-trans
Use current Rust releases for testing

Replace the old, outdated PPA with another one, who builds packages for
recent Rust releases.
Update Changelog
Merge pull request #321 from yasuyk/gmake

Add syntax checker for GNU Makefile using GNU Make
Update changelog and credits

Thank you, @yasuyk, you rock!
Replace dir-locals with file local variables

Set encoding and disable tab indentation for all Emacs Lisp files
Fix indentation
[Fix #319] Do not visit the file to check
Fix Go URLs

The Go website isn't really available over HTTPS
Add URL to Erlang syntax checker
Update hlint URL
Update the chktex URL
Group syntax checker by languages and add URLs
Explain supported languages rather than available syntax checkers

This is more what users expect to read, especially if they are not yet
familiar with the concept of a syntax checker
Turn Flycheck object types into a domain
Count languages and syntax checkers
Update the info manual
Fix typo