Cleaned up thermocouple stuff for adding second TC
Show temps on graph lines, related bugfixes

Added code to show temperatures on the graph lines, on the right-hand
side of the graph.

Wrote the number of bytes required to use each graph option alone.

Removed all use of Color565() and replaced with #define'd values. Saves
72 bytes.

Fixed bug in stop graph on done code that failed compilation of the
option was disabled.
Minor optimizations

Low hanging fruit by optimizing type sizes.

Fixed some flash-related stuff that could save SRAM if ever needed in
the future.