Return amount for CREDITS, POD rework.

Return amount for CREDITS, POD rework.

The main change here is to get an {amount} field for CREDITS,
not just CHARGES.  I also use a fallback to default value (5)
in case noissuescharge has been deleted or set to 0.

POD is reworked to keep the salient chunks
about patronflags in the correct section and format them for
easier reference.  Deprecated display layer code.

Signed-off-by: Galen Charlton <galen.charlton@liblime.com>
Signed-off-by: Henri-Damien LAURENT <henridamien.laurent@biblibre.com>