Lint Variable Case

[nstringham]

related to #1205

In this PR the following changes are made to eslint config:

• you will be warned if you have a let that should be a const
• you will be warned if you break a variable naming rule:
  • Variables must be camelCase
  • Constants that are exported must be UPPER_CASE
  • Classes and Types must be PascalCase

This PR also renames some variables to meet these new requirements

This PR also fixes some other linting errors

NOTE: not all the variable case problems have been resolved. I am leaving some things to other developers/maintainers.