remove old references to dtcwt.backend.base.{...}
remove ReconstructedSignal

ReconstructedSignal was nothing more than a needless wrapper around a
numpy array. There's no need for it.
update REAMDE with removal of ReconstructedSignal
rename TransformDomainSignal -> Pyramid
README: add note on renamed TransformDomainSignal
rename Pyramid.subbands -> Pytamid.highpasses

The higpasses attribute is a sequence of highpass, each slice of which
is a subband. Fix the incorrect terminology before it gets worse.
move 2d transfom compatibility functions to dtcwt.compat
move lowlevel functions to backend-specific modules
add biort/qshift documentation to Transform2d
remove reference to dtwavexfm2 in Transform2d documentation
re-arrange API reference a little
docs/variant: fix incorrect use of code-block directive
fix examples to use new API
docs: fix copyright year
remove unnecessary bits of the docs

The LICENCE and Features of note sections were a little superfluous. The
overview of MATLAB compatible functions was just wrong.
plotting: remove hold(...) calls

The hold(True) calls weren't necessary and the hold(False) call actually
changed the default hold state of matplotlib which could lead to some
strange results.
move the intro blurb to the Getting Started section
docs/index: remove Contents section header

The contents header was messing up the LaTeX output
move 1d transform to new-style API
rename parameter to inverse transform to 'pyramid'