fixed compilation in debug mode, plus minor code tweaks.
Merge branch 'master' of github.com:appleseedhq/appleseed
tweaked travis build: changed git tag to travis-build, enabled verbose mode for unit tests, fixed a typo.
fixed travis build: the git tag must contain a version number of the form <major>.<minor>.<patch>.
fixed and refactored the interface and implementation of foundation::XMLElement.
More OSL attributes work.
Commit for curve uv computation logic
fixed a travis build error wrto access the base class variable
Merge pull request #486 from sriravic/branch_curve_03_pr

Commit for curve uv computation logic
Merge branch 'master' into OSL_updates