Implemented the RTC periodic IRQ generator (better later than never:)
Closes FR#1406011.
There are not too much of those urgently missing/missed parts now.
dosemu now only lacks the proper LPT support, and well, the sound.
The rest is there.


git-svn-id: https://dosemu.svn.sourceforge.net/svnroot/dosemu/trunk@1511 7758b857-130e-0410-ab9c-d8735a528d18