Improving the output when exporting from the GUI to m files.

Following up on various suggestions made by @trefethen.
Ensuring backwards compatability for first order integral equations.
Adding a test for the backwards compatability of int. eqn.
Merge branch 'fix-chebguiExporter-output' of ssh://github.com/chebfun/chebfun into feature-chebgui-periodic
Fixing whitespace in Chebgui exports.
Making datestr in Chebgui exported files more appealing.
Further modifying datestr in exported Chebgui files.
Merge pull request #1287 from chebfun/fix-chebguiExporter-output

Improving the output when exporting from the GUI to m files.
Merge pull request #1295 from chebfun/fix-integral-IVPs

Ensuring backwards compatability for first order integral equations
Adding an periodic EIG demo.
Various changes to make 'periodic' discretization work in Chebgui.
Merge branch 'development' of ssh://github.com/chebfun/chebfun into feature-chebgui-periodic
We now get the titles of plotcoeffs plots automatically!