[DOS] DOSBox Update

DOSBox 0.70

Another year and another dosbox version, again more speedups and compatibility fixes.

Speed up the dynamic cpu core (certain games get much faster).
Add a dynamic fpu on x86 hosts.
Improve the cycle guessing code (and make it default).
Better and more configurable joystick support.
Improve the image and fat drives.
Add nullmodem emulation.
Various win 3.x enhanchments (video/audio/ems/win32s).
Improve CDROM detection and support.
Speed up the screen drawing code.
Add support for different keyboard layouts.
Various fixes to the (C/E/V)GA emulation.
Extend and improve all types of emulated memory. (umb/ems/xms)
Dynamic core should work on Intel Macs.
Various timer related fixes.
Added a few more graphic scalers.