improve Windows command prompt template

Mappings for the Windows command prompt mapped the bright colours to
shades of light/dark, which resulted in weird looking applications.
This new mapping respects the bright colours, and mostly uses the same
colours for the dark and light versions, because the colour schemes do
not have dark and light versions of the colours.

The mapping is optimised for the Solarized scheme. For example, 0F in
Solarized maps perfectly to the purple/pink of cmd, but 0F in other
schemes looks more brown. Brown-ish colours could be more suitable for
the dark red colour of cmd, but Solarized 0F would look stange when
used as dark red. I think this mapping is a good compromise.
Fix highlighted line
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.)
Created a new twilight theme.
Improved the Xcode 4 templates.
Changed back Invisible to different color from background.
Fix "dhex" for xfce4-terminal
Merge pull request #99 from djmason/xfce4-terminal-fix

Fix "dhex" for xfce4-terminal
Allow schemes to be read from an URL

I like to store my schema as a gist and it would be nice to generate the files by just passing a URL to the `base16`
command. This change will do just this.
Added URL example to the README
Merge pull request #100 from railsbros-dirk/read-schemes-from-url

Allow schemes to be read from an URL