DLI improvement

[vitococl]

Allow the assignment of a constant or array to more than one memory address/register, just like it does with WSYNC.

For example, to move two overlapped players to build a multicolor sprite using a single horizontal position array, instead of:
DLI SET mydli = xpos INTO $D002, xpos INTO $D003
it could be great to use:
DLI SET mydli = xpos INTO $D002 INTO $D003

This would save machine cycles during the interrupt by loading the value once, allowing to write longer DLIs without glitches.

In combination with WSYNC, the syntax could be something like this:
DLI SET mydli = xpos WSYNC INTO $D002 WSYNC WSYNC INTO $D003