Improve UI of PacketViewer

A collection of mixed changes:
 - Stop hex split divider from changing location when
   selecting another packet
 - Add alternating row colors in param table
 - Disable table grids
 - Allow "starring" a packet
 - Fix some menu mnemonics

As a result of these changes, both the packet table and the
parameter table were moved to their own dedicated class.
Support searching for an Opsname

When pressing <CTRL-F>, a Find-Bar now pops up in the parameters table.
The bar can be easily closed with <ESC>. All search actions are also
accessible through buttons on the find-bar.

At the moment you still need to press ENTER before it searches.
There's no instantaneous highlighting as of yet.

Note that this commit also includes some changes that remove all kinds
of unneeded borders on the default Swing components.
Merge pull request #10 from fqqb/ui-improve

Ui improve