* Adds the #bitcoin-dev IRC channel, Bitcoin StackExchange, and
BitcoinTalk Dev & Tech board to the development page.
* Links to that section of the page from the devel docs.
Move existing "regtest / testnet" texts to the new subsection and link to it
Move Bitcoin Core setup instructions in devel-examples
Add a consistent introduction for devel-(guide/ref/examples)
Fix autocrossref.rb to not add links inside {% highlight %} code blocks