remove any RTL rule that can be autogenerated

Also add noflip comment marker for things that shouldn't be
flipped. That leaves ones that change background images mostly.
Merge #156
newly renerated moodle.css
move rtl only CSS to their own files

Also added a switching mechanism based on the current language,
note that this will then cache RTL or LTR until the next theme
change so it's not suitable for sites using both directions.

There's still an issue with the columns on the front page, I
think there's some Moodle mechanism for RTL that's fiddling with
the block order and interfering with the basic Bootstrap grid.

edit: actually I think it was just the block swapping stuff at
the bottom of config.php that was causing that, looks better now
that I've deleted it anyway.
expand toggles RTL fixes

The rtl-css-flipper doesn't yet support the background: short
version to converting them to background-image, background-position
etc. and using absolute or percentage values, not pixel as they
are unflippable.
Merge pull request #158 from ds125v/rtl_toggles

Rtl toggles
unbundle background: for rtl-flipper
Merge pull request #159 from ds125v/rtl_filemanager_icons

unbundle background: for rtl-flipper
provide grunt swatch reset option
add cupid bootswatch
update docblock
remove broken code
rename reset option to none
Merge pull request #160 from jobyh/swatch-reset

Grunt clear bootswatch option
Merge pull request #161 from jobyh/bootswatch-cupid

Cupid bootswatch
use grunt-text-replace to flip image names for rtl

Move the last of the RTL out of the core files.

It also lets me escape some weird interaction where
javascript was adding classnames to change the image but the old
RTL solution was adding .dir-rtl and messing up the specificity.
Merge pull request #163 from ds125v/rtl_image_flipper

use grunt sed to flip image names for rtl