Generics
	Naturally, the ability to program generically different associative containers, is beneficial.
The distinction in this library between 
data_type_defs.htmldata_type s and
mapped_data_type_defs.htmlmapped_data_type s, and between value_type_defs.htmlvalue_type s and
mapped_value_type_defs.htmlmapped_value_type s, somewhat complicates this.
	The generic utility classes ease static detection of different associative-container
types (
e.g., whether they are map or multimap types), and the extraction of data from iterators.
