Wow, wonderful work!
As an additional information about already existing execution plan visualisation tools:
Depesz has written the classical PostgreSQL Execution Plan Visualiser years ago.
Of cause it is not so nicely pretty as the one from Tatiyants, but I use it now and then and it became a standard explain visualisation tool for many PostgreSQL users.
The table format from http://explain.depesz.com/ is very useful and one can understand a lot of details about your execution plan without the need to visualise in the form of a graph.
Also the default execution plan visualiser in pgAdmin looks really cool.