Simplify cut set gathering from an indexed fault tree.
Correct a coding standards link in readme file.
Change basic and house events to reflect their use.

Now house events are described by their states only and no probabilities
provided because they should not appear in minimal cut sets.
Separate basic events from house events in an original fault tree.

A separate container is provided for basic and house events in a fault tree.
This containers should make easier the indexation process and house event
state determination.
Introduce original module detection after pre-processing.
Separate complex XOR and ATLEAST gate unrolling from pre-processing.

This is needed for original module detection because unrolling complex
gates creates new gates that are not in original trees.
Fix a typo bug in unrolling complex gates and rename joining function.
Gather parents of indexed gates for future use.
Add experimental inputs for module detection and unity top special case.
Move cut set generation and minimization to simple gate pointers with
modules.
Introduce initial use of modules in fault tree analysis.