Moving trade screen search lines

Now that this screen uses the window's full height, the hard-coded line is no longer appropriate.
Moving Mark/Unmark all in the trade screen

These are in a different plugin, but affect the same interface.
Switching Mark/Unmark all hotkeys to red

Following the policy described in the Readme.
Prioritizing search hooks on the trade screen.

The autotrade plugin has been intercepting the m/u/M/U keys if enabled after enabling the search plugin.  An explicit priority makes the search plugin always accept those keys while typing in a search line.
Merge pull request #289 from eswald/trade-search

Moving trade screen search lines