Create general-purpose terminal emulator base classes

[oubiwann]

Part of epic:

• 21

Tasks:

• [x] Stub out library and UI files (.svg, .cpp, .hpp files)
• [x] Create Shell header for implementation:
  • [x] read
  • [x] eval
  • [x] print
  • [x] loop
• [ ] Create Shell no-ops for testing:
  • [ ] read (no parsing)
  • [ ] eval (echo)
  • [ ] print
  • [ ] loop
• [x] Allow for defining welcome, prompt, and banner
• [x] Get primitive read-print capability in a text area
• [ ] Store entries as vec of strings
  • [ ] maintain a vec for display purposes
  • [ ] maintain another vec for the complete session history
• [ ] Emulate terminal behaviour
  • [ ] only read when last line is change
  • [ ] don't make changes to text area if not made in last line
  • [ ] don't go past max height
  • [ ] when max height is reached, pop off first element from display vec to make room
  • [ ] don't allow edits in the prompt area
  • [ ] add readline suppport
• [ ] Reset button for clearing history and memory
• [ ] Add support for slurping files (definitions)
• [ ] Add support for dumping command history to file
• [ ] Provide a means of setting specific shells
• [ ] Maintain cross-restart command history (module json file?)

Blocks:

• 26

• 24

[oubiwann]

Responding to arrow keys might be a nice first step at emulating readline. Ideas here:

• https://github.com/Dewb/monome-rack/blob/main/src/teletype/screen/TeletypeScreenWidget.cpp