Installation process update

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Replaced 2 scripts with single one.

Improvements: the whole installation process is even more simplified. (This is currently default install which will
be phased out, once new build system works as simple as this one and is adopted by users - might take some time).

- the script has default options, and when run from $HOMEDIR automatically installs everything in a single go.
The options can be changed by flags (build, installation dirs etc, see documentation).

Updated README.md also. In dependencies section I added eigen3, googletest and updated clang-format instructions.