Add uri.jsm -- custom uri schemes.

[fourkbomb]

]addscheme <name> <url>
]delscheme <name>

for example:

<someone> ]addscheme xkcd http://xkcd.com/%s
<someone> xkcd://232
<aucgbot> http://xkcd.com/232

[auscompgeek]

This pull request now suffers from bitrot. Please fix.

[cyphar]

nit: modeline.

[auscompgeek]

I believe this is the modeline included in all my modules.

[cyphar]

I believe that it should be purged. This project must be purified. FIRE UP THE OVENS.