v 0.6.9

Update <head> contents for core and layout.liquid

Change if IE 8 conditional comment to if lte IE 8 for backwards compatibility if needed.

add comments to break point vars

separate out mixins into individual files for better organization
Create fixed element mixin

Convert Tool tips over into an actual placeholder.  Use the new position mixin in place of having multiple different classes.

Kill html overflow-y scroll and min-height.  -- not needed for modern browsers.

create new placeholder %mp-Reset which only resets margin and padding, so we don't' have to cancel out borders and outlines which aren't there by default anyway.

Add %d-Block & %d-None to placeholders

Lots of other clean up to various files.