Eigen Compiler Suite

Right now the default allocators for smaller target is a very simple bump allocator
with no possibility to reclaim memory.

I searched a bit for other options and found a possible replacement which is small
enough to even be used for systems with a few tens of KB of RAM.

The allocator is called TLSF (Two-Level Segregate Fit) and is a relative new development
which has attractive properties for smaller systems and the code size in the range of 500 to 1000 LOC.

Webpage : http://www.gii.upv.es/tlsf/index.html
Paper : http://www.gii.upv.es/tlsf/files/papers/ecrts04_tlsf.pdf
Independent implementation : https://github.com/mattconte/tlsf

An independent implementation can be done from the paper if the license is a problem.

Other alternative simple solutions with linear scanning free lists have problems with
overhead for the smallest systems and fragmentation.