[NES II] Load and execute an Apple DOS 3.3 bin format executable about nesii

[JMarlin]

Started reorganizing to cleanly separate logical layers

[JMarlin]

Did a nice reorg of the build setup today so that NOS can optionally be built into the BIOS ROM image (and jumped to directly instead of the BIOS trying to load the bootsector) so that we can build and test NOS code without having to constantly write floppies.

[JMarlin]

Got a wild hair and ended up getting a mechanism for handing args to subcommands and an echo command to demonstrate it.
Will need this in order to pass a file name to the run command.

[JMarlin]

Just making a note that I did check and confirm that find file is working with support for spaces as potential match terminators

[JMarlin]

Implemented open and read byte FS calls that basically seem to work.
Read byte does not yet support chaining into the next T/S list sector, which we're definitely going to need for loading NES games.

We should probably implement the 'keep reading until the floppy data latch changes' method of waiting for the floppy motor at some point since right now we always wait a little over a second after we turn the floppy motor on just in case.

[JMarlin]

In the interest of making the fully fleshed-out follow-the-whole-T/S-list-chain version of the file read code a little easier to implement, started modifying the code today to operate on the basis of an 'open file info' structure which includes information about what the root T/S list sector for the file is, what the currently loaded T/S list sector is, which T/S is currently loaded into the data buffer, &c.

[JMarlin]

Large file loading now works confirmed up to 16k, now I just need to add a jsr to the entry point and this story is functionally done.
Next step is to open an issue for loading and executing 32k NES games off of the FS.

[JMarlin]

Run command working all day long, need to merge and we're done