Store commonly-occurring code so it can be de-emphasized in the GUI

[louis-hildebrand]

Two similar features suggested by Prof. Dubach:

• Grey out starter code. This is probably simpler. Add a new field starter_code_locations to the backend's output file. It would probably be convenient for the frontend to have it in a format like this:

  "starter_code_locations": {
  	"project1": {
  		"fileA.s": [
  			{ start: 0, end: 100 },
  			{ start: 950, end: 1024 }
  		],
  		"fileB.s": [...]
  	},
  	...
  }
  

  That way, when showing a certain file, it can quickly access the list of ranges that are starter code in that specific file. But it would probably also be fine to just have a list of locations and the frontend could convert it to whatever format it wants when reading the results file.
• Make color proportional to how common code is. This seems trickier to implement.