Created HexViewerView class to remove all globals

Global variables are evil.  I always try to avoid them.
Broke long sequences of commands into separate modules.
Used `tableview1.reload()` instead of closing and recreating tableview1.
User 'rpartition()` to separate path from fullpath.
Initialize pos to be -1
Merge pull request #6 from cclauss/patch-4

Created HexViewerView class to remove all globals