• Build&Snippet: Auto-match ${}
• Build: Enable completions in empty ${} placeholders
• Keymap: Support altgr modifier and plain modifiers as keys
• Mousemap: Highlight and complete buttons up to 16
• Settings: Allow disabling completions and tooltips
  for better interoperability with LSP-json (@rchl, #286)
• Syntax: Fix test completions for <- indicator (@deathaxe, #302)
• Theme&Scheme: Provide completions for inherited and overridden variable names
• Theme: Complete themes for the extends value
• Theme: Completions for variables of extended themes
• Theme: Provide proper completions for parents selectors
• Misc: Minor scoping and completion fixes (partly @deathaxe)