Update the V4 deprecated syntax F(n), for chebop F, to handle the new V5 rectangular discretization style.
Prevent CHEBMATRICES from having non-scalar block entries.

Closes #806.

This entailed some faffing around in LINOP/EIGS() and CHEBGUI, which were guilty of breaking this rule.
Vectorized LEG2CHEB allows vectorized LEGPOLY. This enables us to do legpoly([15000:15004]), for instance.
Add TODO.
Fix a couple of small bugs.
Add deprecation warning for domain-object inputs to ratinterp().

We don't need to use a domain class in ratinterp() to solve dispatching
problems anymore, so it would be nice if we could get rid of it as a
supported syntax in the future.
Ensure LEGEND info is correct when plotting.
Add similar support for PLOT3().
Only throw warning once.
Some tidying up.
Some improvements to eigenmode plotting.
Update DISP and DISPLAY methods.
Minor adjustments to @chebmatrix/disp.
Merge branch 'fix-ratinterp-cf' into development
Suppress warning in test.
Minor fixes.
Split CHEBOP tests in to more manageable chunks.
Add a containing to CHEBFUN2V display output.
Merge branch 'development' into feature-legpoly-cheb2leg
Use norm rather than normalize and respect method selection.