ignore errors on syntax events

If the environment is broken it's not our problem, and the user was
already notified on the initial buffer-load.
filebeagle mappings

To prevent Sneak from changing filebeagle defaults:

    let g:sneak#map_netrw = 0

(For backwards compatibility, we're currently using the
`g:sneak#map_netrw` setting. This will be migrated later.)
use nmap for <Plug> maps
WIP