Add mix, shade & tint functions

Use these in color schemes for some automatic bright & dark versions. They will
even stay in-theme, since the functions will use the theme's defined darkest and
brightest colors.

Shout out to the [Sass](http://sass-lang.com/) & [Bourbon](http://bourbon.io)
projects for the code!
Ensure the results of mix() are integers
Initial Konsole template

Uses the tint function to brighten every color
Rename the colorscheme file

Also, start weighing the source color higher, in my opinion the resulting colors
were too pastel.
Fix red intense

It was using yellow, whoops!
Add a HTML preview to make iteration a little quicker

I'm trying to tweak the tint mix and having to restart konsole every time is
annoying. Use the HTML version for rapid iteration.
Extract the parameter into a single variable

Less magic numbers, and it makes it *much* easier to change the ratio
Reverse the order of the parameters passed to mix

The weight parameter only really works approaching 0, at 100 it still does a
75/25 mix, which isn't really what I intended.
Don't use the original HTML preview comment

It's not the HTML preview anymore, so don't include comments that state
otherwise
Switch the colorscheme to use a ratio variable as well

All the same reasons, easier to iterate/change. (And I'm unlikely to have
color-specific variations...maybe.)
Merge pull request #90 from evaryont/konsole-template

Add mix, shade & tint functions