HTML & CSS consistently use TAB for whitespace
Add git-scm.com link & associated CSS cleanup
Change issue tracker & msysGit links
Upgrade to Lightbox 2.6
Add Javascript to load SVGs if browser supported
Replace the Javascript way to replace .png with .svg with a pure CSS one

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Proof of concept: start supporting small screens

This is only a proof of concept because there are really a *lot* of
assumptions in style.css regarding a minimal width of 700 pixels and a
maximal one of 900 pixels.

In other words: this commit is not meant to be merged as-is but to
demonstrate where things need to go before being mergeable.

It would be best, of course, if the .css changed for smaller widths
regardless whether it is a mobile device or not, for one.

Also: the small-screen stuff might be cleaner in a separate .css file.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Rename font directory to the more standard fonts.
Move lightbox files in the appropriate individual directories.

Also remove the unused screen.css and modernizr.custom.js.
style.css: remove trailing spaces.
Fix validation errors.
Consistency changes.

Use https for github links, remove unneeded end tags.
fonts.css: remove useless new lines.
Losslessly compress PNG files.
Convert the thumbnails to 8-bit.

gw1web_thumb.png | Bin 12394 -> 5724 bytes
gw2web_thumb.png | Bin 12514 -> 5748 bytes
gw3web_thumb.png | Bin 17703 -> 7841 bytes