add a long form block escape:

terra foo()
  escape
    --multi-statement Lua code
    emit quote return 1 end -- emit function bound in escape to insert code into surround terra code
  end
end

Similar to strings, function calls whose only argument is a quote (long or short) do not require parens.
This eliminates the awkward parens around the emit function inside escape blocks.
Merge branch 'master' of github.com:zdevito/terra