This the first part of a series to allow nodes to write all of their appropriate
pieces to the class. Currently, nodes must add their bindings, constants, and
functions to main SClass node for delayed writing. This instead adds a
Painless version of ClassWriter to the write pass. The Painless ClassWriter
contains an appropriate ClassVisitor that can be accessed in any node
during the process along with access to the clinit method, and finally a
shortcut for creating new MethodWriter. The next step will be removing the
delayed writing in SClass, and instead, delegate all writing responsibilities to
the nodes.