prepost_diag_connection_impl
============================

A connection for two layers with the same representation.  First multiply
the output of the source layer element-wise by a set of input multipliers;
matrix multiply these in the same manner as diag_connection_impl; and then
multiply element-wise by a set of output multipliers and use the resultant
values to set the input of the target layer.

Parameters
----------

	parameter	default_value
	excitation	0
	inhibition	0

set_input_multipliers
---------------------

	some_ppconn set_input_multipliers vrep

Use a vector representation `vrep` to set the input multipliers of `some_ppconn`.
A conversion from the representation of the source layer to this representation
is used to establish the corresponding value.

set_output_multipliers
---------------------

	some_ppconn set_output_multipliers vrep

Use a vector representation `vrep` to set the output multipliers of `some_ppconn`.
A conversion from the representation of the target layer to this representation
is used to establish the corresponding value.