fftplan.Free
gui: setmesh, prepare for free
cleanup free
fix magnetization normalize w/ volume
minor cleanup
slice len now int
all but ext/ compiles with Mesh() removed from Slice
mumax3 main compiles
don't build tools for now
update cuda tests
update data test, do I/O later
fix test/antenna.go
resize test + a few Free() fixes
mv ovf2 to data/
split of data/meta.go
use ovf2 output by default
autosave: .ovf file name
fix ovf out-of-bounds error
ovf: fix data order
stricter resize test