#549 Make the parser understand multi-line commands

[doncherry]

Syntax highlighting/recognition doesn’t work if the \usepackage{...} macro is broken arcoss two lines:

\usepackage[someoption
   ]{lipsum}
\usepackage{
   blindtext}
\lipsum
\blindtext

If I understand correctly, this is an issue not only limited to \usepackage, but to all macro parsing.

(This is a follow-up to [bugs:#809].)

[Tim Hoffmann]

This is now supported since 2.11.0