Include .editorconfig

http://editorconfig.org/
Refined .editorconfig
typo
Fixes #7648: Thumbnail caption should use @text-color variable. Also adds other thumbnail vars
Fixes #7617: lowercase and dash gray color vars
Use* global rules with exceptions as needed
'root' repo end 'insert_final_newline = true'
Fixes #7661
Merge pull request #7662 from cvrebert/less-1.4-fixes

Fixes #7661
Merge branch 'ntwb-editorconfig' into 3.0.0-wip
explicit callout in readme for building static assets; fixes #7632
shoutout to editorconfig in readme
Merge branch '3.0.0-wip' of github.com:twitter/bootstrap into 3.0.0-wip
'root' folder .editorconfig code guide updates
'less' folder .editorconfig code guide updates
'js' folder .editorconfig code guide updates
'docs' folder .editorconfig code guide updates
Merge pull request #7664 from ntwb/editorconfig-3.0.0-wip

Editor Config (.editorconfig) Code Guide Update
More distinguished state of toggleable buttons

Use darker colors for .btn.active (i.e. pressed) state when button is
set toggleable via data-toggle="button...". Also after button is pressed
it becomes brighter on :hover, :focus, :active.

So when button is in the released state hovering over makes it darker
as default, but after clicking on it the color becomes even darker and
it easy to see that the button is pressed. On the other side, hovering
over the pressed button makes it brighter and clicking on it brightens
button further.

This not only helps out to see easier the current button state
but also shows which way the state will change.
Add delimiter option to typeahead

If delimiter option is not false autocomplete only last part

Its value is converted to RegExp with m(ultiline) modifier.