Rakudo compiler architecture

Described in docs/compiler_overview.pod

Based on Parrot Compiler Toolkit (PCT)

• parse grammar (src/parser/grammar.pg, src/parser/*.pir)
• -- converts source to parse tree

• parse actions (src/parser/actions.pm)
• -- builds abstract syntax tree from parse

• main compiler object (perl6.pir)
• -- handles command line options, initialization

• builtin functions and runtime support