Incomplete draft of README.md.
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.
Ensure LEGEND info is correct when plotting.
Add similar support for PLOT3().
Some tidying up.
Some improvements to eigenmode plotting.
Update DISP and DISPLAY methods.
Minor adjustments to @chebmatrix/disp.
Minor fixes.
Add a containing to CHEBFUN2V display output.
Merge branch 'development' into feature-legpoly-cheb2leg
Use norm rather than normalize and respect method selection.
Fixing up VERTCAT.
Adding a test.
Throwing a warning and stripping BCs.
Merge branch 'development' into fix-ATAP-chebop
Update tests.