finally renames 'bios' to 'SAKURA'; add some minor improvements.
some improvements on integration modules and PN stuff.
split C/CL implementations in different files (I).
split C/CL implementations in different files (II).
split C/CL implementations in different files (III); also the interface for building extension modules has been improved.
minor improvements.
try to implement a variable time step size in sakura (not finished yet). added some improvements in other modules.
now Sakura is using an adaptive timestep size.
A major reworking of C/CL extension modules and related stuff aiming to make things easier for vectorize kernels in the future. Also includes some random improvements in other modules.