Clean up store.c store_object_similar() and fix a bug.

The test for well-balanced items is broken.
Make sidebar hp color match @ color
Items sold in each shot can now be specified in the object.txt file (coded by "Runningaway")

Signed-off-by: nppangband <nppangbanddev@verizon.net>
Merge pull request #56 from nppangband/work_in_progress

Sync with Work in progress