Tracing module execution

The trace verbosity is introduced between the verbose and debug levels to report details on module searches, resolutions, selections and evaluations. Trace mode can be enabled by setting the verbosity config to the trace value or by using the -T/--trace command-line switches.

To specifically render trace messages, the tr key is added to the color palette with a default value of 2 (decreased intensity).

$ ml -T foo
Evaluate modulerc: '/path/to/modulefiles/.modulerc'
Get modules: {foo} matching 'foo' in '/path/to/modulefiles'
Resolve: 'foo' into 'bar'
Get modules: {bar bar/1.0} matching 'bar' in '/path/to/modulefiles'
Select module: 'bar/1.0' (/path/to/modulefiles/bar/1.0) matching 'bar/1.0'

Loading bar/1.0
Evaluate modulefile: '/path/to/modulefiles/bar/1.0' as 'bar/1.0'