Deleted Silylene_Elimination family.

This reaction family was causing problems, for some reason. Since it is the opposite of
Silylene_Insertion, it's probably not necessary, as we have the ability to add training
reactions in the other direction to families.
Changes to Silylene_Insertion and Silylene_to_Silene families.

Added a forbidden group to Silylene_Insertion: do not let a siylelne's Si-H bond be inserted into. Added top level node rules for both families. Made the label for a group in Silylene_to_Silene more general.
Modifications to thermodynamic properties of Si containing groups.

Added some groups and entered values for some top level nodes based on the
children nodes. Also made sure that a radical group for Si was defined properly,
by putting into new adjacency list style.