Make outer quote text object include next whitespace

There was an inconsistency with Vim: `a"` there actually selects the
quotes plus any extra whitespace to the right of the quotes. Instead
`2i"` should be used to select everything - including the quotes - but
nothing extra.

Related to #522.

Users should be warned that this behavior changed; if they want the old behavior (different from Vim) they can put the following in their `.vrapperrc`: 

````
onoremap a' 2i'
onoremap a" 2i"
onoremap a` 2i`

vnoremap a' 2i'
vnoremap a" 2i"
vnoremap a` 2i`
````