refined BATsetaccess  such that a change from BAT_WRITE to BAT_READ for a temporary MAP_STORE heapdoes not need to unload and re-map anymore.
refined BATsetaccess  such that a change from BAT_WRITE to BAT_READ
for a temporary MAP_STORE heapdoes not need to unload and re-map
anymore.

zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb