New releases for the LM80C Color Computer firmware.

In the last days I've released the R3.12 and R3.13 files. They contain a lot of bug fixes and enhancements. Here is the cumulative changelog:

• - New style for "£" char;
• fixed a bug into the automatic shutting down manager of SOUND that didn't de-activate the audio channel into the PSG mixer after a tone had finished its period of reproduction;
• new INSTR statement, returning the position of the first occurrence of one string within another;
• changed the behavior of INKEY statement: now the minimum delay interval is set to 10 hundredths of a second. If a shorter interval is being passed, it will be automatically set to 10 (this is because values under 10 could lead to faulty readings);
• fixed a severe bug originated by a wrong design error of the final PCB: ports A & B of the PSG were inverted into the schematic, same for the definition of the ports into the code;
• fixed a bug into the SOUND statement that accepted the third argument when generating a noise, even the syntax shouldn't accept it.

Please grab the latest revisions from my Github repo.