Estimate an upper bound on the number of particles to read into the cache and how many particles to loop over in DOPAIR2_VEC.

Removed alternate version of doself2_vec that was slower than current version. Renamed some variables. Removed left-packing functions for force interactions as they are not used anymore.

Created new version of doself2_vec that computes force interaction on the fly, 2.1x faster than serial.

Corrected bug in last_pj calculation. Using the last active particle in the cell as the upper bound now works.

Fixed seg fault bug. Make sure that max_index_i[ci->count - 1] and max_index_j[0] are initialised to correct values when nothing is in range.

Fixed seg fault bug. Make sure that max_index_i[ci->count - 1] and max_index_j[0] are initialised to correct values when nothing is in range.

Use hi_max and hj_max instead of particles own hi to work out how many particles to read into the cache.