Provide filename sans extension to hook

[Andrew]

Either just as a third argument:

babel $1 > ${3}.es5.js

Or provide a framework to fiddle the arguments around. Keywords on the RHS side of these option rules will correspond to the types of values you can pass.

# vimhook.args.1 = filename
# vimhook.args.2 = event
# vimhook.args.3 = basename
# vimhook.args.4 = dirname
# vimhook.args.5 = timestamp