Add Error Log to Errors Tab

Include an error log in the "Errors" tab to help in future debugging
efforts.  Only tracks errors that eventually arrive in the other
indicators on the Errors tab.
Disable TableHistory Diagnostic Info Capture (#69)

Since most users don't use the diagnostic info about current table history
depth, we can disable the subdiagram that generates it.  This should
eliminate a local variable read AND an unbundle that was occuring
with every table click, possibly making the table interface even faster.

Continues work on #69, seems fairly responsive on my machine now.