Pre-Release 3.0.0a2

• Removed Parser2 and related infrastructure. It was already replaced by Parser in
  previous release, but I didn't have time to make sure all of dependencies were gone.
• Removed most of the old documentation.
• Moved pygerber.gerberx3 to pygerber.gerber. I acknowledge this is a breaking
  change, but using gerberx3 as a package name when it in fact contained code mostly
  compatible with more than just X3 was misleading.
• Moved pygerber.gerber.ast.builder to pygerber.builder.gerber.
• Moved pygerber.vm.builder to pygerber.builder.rvmc.
• Added new documentation layout.
• Added documentation for GerberX3Builder from pygerber.builder.gerber module.
• Added Quick start guide to documentation.
• Added pygerber.gerber.pygments, a Pygments lexer for Gerber files. To use it you
  have to install pygments extras package (or just have pygments installed from other
  source).
• Added support for deprecated syntax construct of D01 with code omitted.
• Changed pygerber.gerber.formatter API and structure. Formatter options are no longer
  directly passed to Formatter class, they are stored in dedicated Options class.
• Added 2 high level formatter API functions available in pygerber.gerber.formatter:
  format, formats.
• Improved docstrings in pygerber.builder.gerber
• Improved pygerber.gerber.formatter docstrings, especially ones related to formatter
  options.
• Changed pygerber.gerber.api to use pygerber.builder.gerber. This is a major change
  in how this API works. I am planning to create some guide on how to migrate code from
  PyGerber 2.4.x to 3.x.x, there is placeholder docs page for that.
• Deleted implementation of command line interface. Unfortunately, command line
  interface is not functional right now.