Bump up version number for new release

bumping up the year to 2017 before v5.6.0 release

updating Contents.m, bump revision number for v5.5.0 release

Bump version number to 5.4.0.

Bump version number in Contents.m for v5.3.0 release.

Bump version number in Contents.m.

Release v5.2.0.

Merge pull request chebfun#1330 from chebfun/fix-chebgui-IVPs-3

Fix chebgui iv ps 3

Update Contents.m with new revision number.

Adjusting tolerance to make sure that chebop/test_eigs_orrsom.m passes.