Switching to a proper memory-pool implementation

[kabicm]

The current implementation allocates one large piece of memory from which all the buffers are taken. This has its advantages, but adds the requirement that all the required memory must be available as one, consecutive piece, which might not be possible in case of fragmentation (see here).

We want to switch to using a proper memory pool.

[kabicm]

This is a reasonable improvements, but doesn't seem to affect the production runs, so we will close it now. We might reopenn it at some later point.