Updating four->trig in the Guide.
adding a chapter for trigfuns.
Shuffling Guide chapters, inserting chap11 before parts about Chebfun2.

I changed all internal references that I could find.

Closes #9.
Removing a space.
Updates of guide01.m for v5.1 release
Updated guide02.  But there are still deltas bugs.
Updates to guide03.m (e.g. referencing Boyd book)
Updates to guide04 for v5.1 release
Update guide05 for 5.1 (but note issue 1291)
Update guide06 for v5.1
Updates to guide07 for v5.1.
Updates to guide08
Update guide09 for v5.1
Updates to guide10.m NOT yet complete
removing unnecessary space around displayed eqs
Finally guide10 is updated (except solveIVP)
solveIVP -> solveivp
Changes to guide11.m, but not done yet
guide11.m is now updated (still needs polishing)
various updates to the Guide