travis.yml changes:

travis.yml changes:
 - Add shorthand-variables for some of the long parameters often used
 - Enable --warn in a couple configure tests that did not have it enabled.
 - Make travis print out CMakeError.log or configure.log in after_failure.
 - Reorder some cmake parameters to improve consistency
 - Disable ccache. Downloading and uploading the cache archive is quite slow,
   especially if travis is having network-connectivity issues.
   Also ccache caches gcno (coverage) files, making the coverage data wrong
   because it is being shared across builds, branches and PRs.

CmakeLists.txt changes:
 - Enable -Wall by default in cmake.