Add D programming language support
Improve formatting of documentation
[Fix #179] Highlight error symbols by default

Error sexps were way too slow for some modes.
Improve error navigation

Navigate errors by looking for overlays, instead of filtering the error
list.  After all, overlays are what the user sees.
Merge branch 'symbol-highlighting'

* symbol-highlighting:
  Improve error navigation
  [Fix #179] Highlight error symbols by default
  Improve formatting of documentation
Fix universal prefix arg to flycheck-next-error
Remove outdated documentation pieces
Use latest packages for tests
[Fix #192] Handle optional line end column
Add separate CoffeeScript syntax checker [#192]

Coffeelint fails to handle syntax errors from Coffee properly.  I love
the Coffeeline developer's attitude towards code quality and backwards
compatibility…
Install CoffeeScript for unit tests
Don't install latest packages with npm

The NPM provider fails to handle latest packages which are already at
the latest version, see puppetlabs/puppetlabs-nodejs#43.
[Fix #184] Parse Pylint 1.0 output

Support for Pylint before 1.0 is dropped.
Include message IDs in Pylint error messages
Fix npm package installation

Regression from fcc62cf.  Pretty damn stupid mistake :(
[Fix #180] Add xmllint checker by @jwalt
[Fix #166] Do not re-display the same errors again

Do not display errors if these errors are already displayed in the error
list.  Prevents excessive filling and re-centering of the error list by
error display.
Remove unused function
Replace -map/-flatten with -mapcat
Install Python checkers with current setuptools

Should hopefully fix Python errors on Travis CI