streamline improvements

move some streamline stuff around, and print some info while tracing

streamline improvements, adaptive RK12 is still a bit crap
necalc improvements

calculator improvements

add convenience necalc class

add untested numexpr only dot and cross products

cross product now tested and looks ok

calc hacks

add untested scalar mil

add untested sum
add n_times to grids / datasets

fix matplotlib scatter plot colors, oops

put **kwargs though all mpl functions

more clear error for field not found

fix point seeds

fix seed.Points again

automatically tighten… this is not an old plt friendly change

sublime text project: ignore build folder

general bug fixes and missing features

linux doesn't like bash -l in the shebang

refactor: mpl.plot_field_lines() -> mpl.plot_streamlines()