* Convert js/ram to a class
* Convert js/mmu to Typescript
* Convert js/apple2io to Typescript
* Convert js/canvas to Typescript
* Use new types in js/mmu
* Rename js/symbols.js to js/symbols.ts
* Remove the difference between readPages and writePages
As @whscullin said in PR #38, there's no need to have both readable
and writable pages since all implementations are currently both. This
change combines them into `Page`. Likewise, `PageHandler` now extends
`Page`.
`Apple2IO` now implements `PageHandler`. This caught a bug where `end`
had been renamed `endend` by mistake.
There are a few other formatting changes as well.
* Convert js/apple2 to Typescript
* Convert js/prefs to Typescript
* Convert all of the ROMs in js/roms to Typescript
Now all of the ROMs are classes that extend the ROM class. There is
some rudamentary checking to make sure that the length of the ROM
matches the declared start and end pages. (This caught what looks to
be an error in roms/apple2e, but it's hard for me to tell.)
The typing also caught an error where the character ROM was being
used for the main ROM for the apple2j version.
* Convert js/roms/cards/* to Typescript
* Convert js/formats/format_utils to Typescript
This change also seems to fix a bug with `.po` image files that
weren't being read correctly.
