SystemVerilog language support in Atom

Adds syntax highlighting and snippets to SystemVerilog files in Atom.

This an update to Razer6's language-verilog, originally done in order to have Atom make the distinction between Verilog and SystemVerilog (thereby avoiding linter complaints about non-Verilog code and adding some bits to the script package that'll allow me to run Verilog and SV files differently).