Split rose-rug-suite into parts I and II.
Run through tidy.
Add suites II mention.
Correct cover slide.
Update CHANGES.md
tests: ensure test suite is tidied up
Merge pull request #1453 from arjclark/split_rose-rug-suites

rose-rug-suites: Split rose rug suites
Merge pull request #1455 from matthewrmshin/tidy-up-after-a-test

tests: ensure test suite is tidied up
Test battery: fix xxdiff dependency

Tests were requiring xxdiff to be installed. This fixes the problem, and
allows developers to configure their favourite `difftool` when running
the test battery. The default is to print a unified diff to STDERR.
Merge pull request #1457 from matthewrmshin/fix-t-xxdiff

Test battery: fix xxdiff dependency
Bring html documentation for rose mpi-launch up to date.
Merge pull request #1459 from arjclark/update_cli_doc_mpi_launch

documentation: Update html documentation for rose mpi-launch
Update for release
Update CHANGES.md
Update CHANGES.md
rose host-select: improve performance

Don't SSH all hosts if ranking method is random and there is no
thresholds to consider. Shuffle host list, and return 1st available
host.