Generated from `bundle gem gerber`

With a few modifications (removed version.rb and filled out the gemspec)
Initial support for reading Extended Gerber (RS-274X) files

This iteration doesn't support aperture macros or outline fill
Moved layer parsing to Layer::Parser
Removed the draw property from Layer::Parser

Wasn't used in a way that couldn't be better handled by the dcode property
Moved Mcode parsing out of Layer::Parser
Store the generated Layers in the Gerber object
Fixed Gerber layer name parsing
Moved top-level parsing into Gerber::Parser
Cleaned some leftover stuff in Gerber::Layer
Added Layer::Parser::DCodeError