Due to lots of cases which were added and added to tree_move(), the function
was not really easy to understand. For this refactoring, I wrote tree_move()
from scratch, thinking about (hopefully) all cases. The testsuite still passes.
The move command also has different parameters now. Instead of the hard to
understand 'before v' stuff, we use 'move [left|right|up|down]'.
You can use this in testcases to mark specific sections:
$i3->command('nop before trying to crash')->recv;
leads to the following output in the i3 logfile:
-------------------------------------------------
NOP: before trying to crash
-------------------------------------------------
