e.g. kilobytes)  of the disk (not just the "free space").

problem better):
* Re-assert the "RX data" interrupt after the rx data register is read and
  there is remaining data.
This also allows us to only signal the interrupt event for *enabled*
interrupts (which certainly seems logical).

A few minor cleanups.

hung threads are hanging while attempting to lock a destroyed semaphore.

Kill blinker/mouse threads before return.

value of the programs main() function.

returns... this means that the user has closed the program, so we can't
very well wait for the program to exit normally can we?

function to run in the *real* main(), with an exit function which is called
after the programs main() returns (to clean up).

only wake-up interrupt_thread() when *asserting* an interrupt.

PlatformSDK.

with single-thread programs which use SDL audio.

Someone should test tone under Linux with SDL audio...

fields (i.e. to/from/subject)