Copyright 2017 Holger Vogt
New BSD license.

A local garbage collector, especially for shared ngspice (ngspice.dll)

Experimental, and not yet tested under LINUX.

All memory allocation and deallocation only via functions given in alloc.c.
Each time any memory is allocated, an entry is made into a hash table, storing the address.
Each time memory is freed, this entry is removed again. Reallocation uses both procedures.
Function mem_init() initializes the setup.
Function mem_delete() frees all memory with addresses still found in the hash table.