quite a load is still hidden behind the define #ifdef _work_on_sb_solver

a glance to view is the "STU PID semi implicit euler"
most of the work to implement a semi implicit euler was done ..
now i am dealing  with the tradeoffs between 'calculation time' which is quite expensive .. inverting a 0(n*n) sparse matrix /* once agian thanks to brecht for his work on making sparse matrices LU decomposition and evaluating inverses that easy*/  putting it into and cropping works pretty nice .. argh off topic again
...
while i spent a little time on reading recent papers i found :

1. control on springs needs to be split in pushing and pulling  /* fabric pushes easy but pulls hard */
2. diagonals on 4-gons (in the current SB model) can be seen as shear .. thus need a contol to modify .. this commit wil add it
3. 2 nd order springs /*aka rigidity */ can focus on bending .. thus renaming 'em
 
i have no idea how i would provide backward compatiblity, but the spots i marked in code :)

source/blender/blenkernel/SConscript

@@ -8,6 +8,7 @@ incs += ' ../python ../render/extern/include #/intern/decimation/extern'
 incs += ' ../imbuf ../avi #/intern/elbeem/extern ../nodes'
 incs += ' #/intern/iksolver/extern ../blenloader ../quicktime'
 incs += ' #/intern/bmfont'
+incs += ' #/intern/opennl/extern'
 
 incs += ' ' + env['BF_OPENGL_INC']
 incs += ' ' + env['BF_ZLIB_INC']