fix: Update TestFlight (#473)

feat: Add --aif option to compile.lua (#471)

fix: "View Source" in welcome app was broken

Also used some more named constants rather than magic values in the
event parsing, and stopped ctrl-shift keyboard shortcuts from being
able to trigger the ctrl-only commands.

fix: compiler error when using MENU with no arguments (#469)

fix: Assorted compiler fixes (#466)

* Incorrect arguments to CLEARFLAGS, DATETIM$
* Wrong return type for PEEKB, PEEKW
* Lack of zero arguments check for MIN/MAX/MEAN/STD/SUM/VAR
* Lack of argument count check for mPOPUP
* Correct min argument count of IOC()
* Renamed `XxxVarArg` to `XxxVariable`

fixes #465.

fix: Add missing opcodes to compiler (#463)

fixes #462

fix: Much refactoring to graphics

* Move text rendering Lua-side.
* Simplified digit font to use 32x8 font bitmap like everything else.
* All Canvases are now internally backed by a 32-bit buffer, to simplify
  rendering.
* All custom inverted drawing logic moved from Canvas to CGContext,
  CGContext.draw() now being given direct access to the Canvas backing
  buffer to facilitate that.
* Direct (non-CoreGraphics) line drawing logic now used for all modes,
  not just inverted, for consistency (no more hairy lines as a result).
  Also fixed off-by-two error in that logic when drawing lines with
  negative x or y direction.
* Box drawing also updated to use direct line drawing.
* All invert operations now supported on colour drawables as well as
  greyscale ones.
* Invert supported on all gCOPY (and now by extension, text rendering)
  operations.
* Improved performance of text rendering with optimised .copy and .mcopy
  operations.
* Canvas.swift and CGContext.swift no longer rely on anything from
  UIKit.
* More consistent support for gSETPENWIDTH.
* Be bug-compatible with allowing negative colour values in gCOLOR.

fix: Implement SIAutoSwitchOffBehaviour:, SetAutoSwitchOffBehavior:()

fix: Implement WEEK()

fixes #438

fix: compiler: support ADDR on array subscripts (#454)

fixes #452