F3 to edit current config file

Remaining to do: figure out how to get default config
somewhere that bpython can find it (actually install it somewhere)
urwid: Use the correct repl variable

repl is imported from bpython, myrepl is the actual object.
manual_readline refactor
yank working!
Merge pull request #362 from lu-zero/master

urwid: Use correct repl
Merge branch 'pastebuffer-keys'
Adds readline keys. ctrl-y and meta-y both yank for now
Make sample config used as template for new config file
reference config docs and fix typo in config
fix tests to deal with kill functions
fix send_current_block_to_external_editor
first draft of incremental search (ctrl-r/s)
don't include current search string as target for incremental search
incremental search and reverse working alright

not very tested yet
Change hardcoded incremental search keys to meta (esc+) r and s
Merge branch 'edit-config'
Merge branch 'reverse-incremental-search'
fix #366 and fix #367

adds tests for and fixes external communication, and
turns off welcome banner if help key is disabled
stop painting standard error red
add new interactive interpreter subclass with pretty pygments traceback coloring
Incorporate new interpreter class into the main repl and use our write traceback method to send to standard error.