Use <LocalLeader>

Use <LocalLeader> for filetype-specific maps so user-defined local
leaders work. Recommended by :help maplocalleader
Use noremap for main mappings

Use noremap where possible to prevent breakage when users remap certain
keys. (Some people swap : and ; which would break all calls to :python)
Use noremap and mode-specific maps in shell buffer

Using noremap will ensure maps still work for users who remap core vim
keys (like :).

Some maps only make sense in normal mode, so only map them there.
Use <Plug> for filetype maps

Use <Plug> for plugin maps to make it easier for users to define their
own maps.

<Plug> names are wrapped in braces to ensure that RunLine and RunLines
aren't considered overlapping by vim. (Otherwise, vim will pause after
RunLine to make sure you don't want RunLines.) See also:
    http://stackoverflow.com/questions/13688022/what-is-the-reason-to-parenthesize-plug-map-names

Plug names have common prefixes (Plot, RunLine) to make completion
easier and grouping clearer.

Note: You cannot use noremap for Plug (it won't map to anything).
Only map within the python buffer

Adds <buffer> to all plugin maps.

Only apply the maps in the current buffer to prevent them from carrying
over into nonpython buffers (where the commands wouldn't make sense).
Comment out unimplemented debugging maps

Hide these from users since they are currently unimplemented.
Merge pull request #55 from pydave/vim-mappings

Clean up mappings: LocalLeader, Plug, and noremap

closes #35