Decrease interrupt stack size
Use __ROR instruction in flash.c for checksum rotate
Fix erase background for frequencies string in plot.c
Implement getStringIndex function for parse string arguments, now Usage show correct information about used arg, and more easy use strings definitions
Example:
Need check if string "on" in avaible arguments list "load|open|short|thru|isoln|done|on|off|reset|data|in"
getStringIndex("on", "load|open|short|thru|isoln|done|on|off|reset|data|in") return 6
If not found return -1
Not need use if (strcmp() == ...) else ....
This usage save some amount of size