More refactoring and code cleanup

v1.2.3

Merge branch 'devel' and bump version to 1.2.3

Catching errors and code cleanup

v1.2.2

Added jQuery UI in license

Bug fixes for various browsers

v1.2.1

Ignore new marker if same as previous (fixes #3)

Supports adding marker while computing

And nice slope computation

Nicer messages while loading & computing

Also, started some refactoring to have a nicer way to handle markers.