Add information about VirtualBox image.
[skip ci]
Initial Fault Tree preprocessing by combining the same type gates.
Further optimization of application of Boolean algebra.

The tree is compacted by joining gates with the same type.
The performance optimization for tree expansion is around 4 times.
Add submission of tests to CDash.
Configure to submit test coverage to CDash.
Add documentation about CDash.
[skip ci]
Fix distribution plotter bug.

The bug was reported by Coverity. The iterator was dereferenced
while it reached the end of the container.
Merge branch 'develop' into coverity-scan

Conflicts:
	.travis.yml
	README.rst
	doc/fta_mcs_algorithm.rst
	doc/scram_coding_standards.rst
	input/speedlog.txt