Update editor settings (minimap and settings for R/C code)

[hturner]

This fixes #285 to only show the minimap on mouseover and also refines the editor settings, according to r-devel/r-dev-day#105 (comment), copied here to include the comments

{
  // Editor settings for C files
  // Cannot set to auto replace 8 spaces with tab (https://github.com/Microsoft/vscode/issues/ #42740, #5394)
  "[c]": {
    // An indent is 4 spaces
    "editor.indentSize": 4,
    // But display 8 spaces as a single tab
    "editor.tabSize": 8,
    // Need this to get indent size 4, else uses tabs to indent
    "editor.insertSpaces": true,
    // If set true, detects settings from the code in the file
    "editor.detectIndentation": false,
  },
  // Editor settings for R files
  "[r]": {
    "editor.indentSize": 4,
    "editor.tabSize": 8,
    "editor.insertSpaces": true,
    "editor.detectIndentation": false
  },
  // There isn't a formatter that works great with R itself
  "editor.formatOnSave": false,
  // Shows the difference between 4 spaces and 8 spaces (tab) visually
  "editor.renderWhitespace": "all",
  // Show whitespace changes in the diff editor to help us get it right
  "diffEditor.ignoreTrimWhitespace": false,
  // Trim trailing whitespace after a line, or on a blank line.
  // You may need to turn this off in some files where historically
  // trailing whitespace has not been trimmed, but otherwise it is
  // good practice to trim it.
  "files.trimTrailingWhitespace": true,
  // Turn off {languageserver} linting for R files
  "r.lsp.diagnostics": false
}