* new: time_helper, types
* new: path_desc
* new: base_desc
* Re-organised objects inheritance
why:
Previous code used macros to instantiate opaque object references. This
has been re-implemented with OO inheritance based logic.
* Normalised trace macros
* Using distinct types for Hash256 aliases
why:
Better control of the meaning of the hashes, all or the same format
caveat:
The protocol handler DSL used by eth66.nim and snap1.nim uses the
underlying type Hash256 and cannot handle the distinct alias in
rlp and chronicles/log macros. So Hash256 is used directly (does
not change readability as the type is clear by parameter names.)