Add bare code expressions

[c4lliope]

On many occasions, drag-and-drop page editors can't live up to the expressiveness of bare code.
Hierarch Pose should not present any barriers to programmers who wish to express their ideas in code.

Since Hierarch Pose uses basic source code files as a storage medium,
this issue falls more along the lines of "don't get in the way" of the user,
rather than "enable" some complex behavior.

Bare code should, in places, be accessible and changeable in the browser-based editor.