URI Support. Mostly written by Luke-Jr. #182

This change supports bitcoin: URIs in bitcoin. It is being resubmitted due to git repo issues on my end (yet again). Sorry about that.

Forums thread here: https://www.bitcoin.org/smf/index.php?topic=6205.0

Does this work "out-of-the-box" on Windows/Mac/Linux in Firefox/Chrome and Safari(mac) and IE(windows) ?

Does it do something reasonable if you click on a bitcoin URI if you don't happen to have bitcoin running?

And is there a solution for bitcoin URIs that works if you use an online wallet service?

Windows? yes, should work in any app which uses Window's native uri mapping, that means safari (win) IE, Firefox, etc, etc, etc. Linux? That is always done at the packaging level. For this to work, Bitcoin has to be packaged for the distro (as URI mapping depends on the distro). If wx2.8 gets merged, Bitcoin-wx will be in the Debian repos pretty quick, and Ubuntu not long after. I've been thinking about putting up a personal package archive on launchpad for older versions of Ubuntu/Debian (as bitcoin-wx/bitcoind will only be packaged officially in the next Ubuntu release, and only in stable in the next Debian release). Mac? That is a bit tougher. AFAICT, mac URI/URL registering requires the use of special APIs that are Mac-native. As I dont have a Bitcoin build-environment setup on a mac, I can't really spend much time experimenting with it (I may have not done enough research and there is a way to handle URI calls the same way every other OS does, ie 2nd parameter to Bitcoin is the URI/L, but maybe a Mac developer can comment here).

Bitcoin already running? Yep, if bitcoin is already running it will send the send message to the send queue of the existing Bitcoin, otherwise it will open Bitcoin and load the send dialog as soon as Bitcoin is initialized.

Online wallet services? That one is a bit trickier. I know the existing chrome RPC plugin accepts bitcoin: URIs, but plugins are the wrong way to do that here. If a web site wants to register a URI on most OSes, it has to have some native client of some kind in the OS. If a web-wallet services has that, they need only register bitcoin: URIs and then let the system decide which to use (Windows + Ubuntu both have a control panel thing to let the user control this, Id assume other OSs/distros as well)

I did a bit more research on doing URIs in OSX as I would like to see this merged some time and there is no way to handle URI/Ls in OSX except by using their native APIs (they dont just pass the URL as a parameter like every other OS) or some kind of wrapper script which handles URIs and opens Bitcoin. As both of those are both terrible solutions, I dont think it is a good idea to bother with URI/L support on OSX until someone does a native UI for OSX.

Implemented in bitcoin-qt