ASIdiSPIM: automatically calculate slice timing on plugin init, also make sure 0.25ms of reduced period in optimized easy timing remains in un-optimized easy timing

git-svn-id: https://valelab.ucsf.edu/svn/micromanager2/trunk@14772 d0ab736e-dc22-4aeb-8dc9-08def0aa14fd
mmstudio: Fix issue reported by Jon Daniels that zstep distance is not reliably propagated to ImageJ metadata

git-svn-id: https://valelab.ucsf.edu/svn/micromanager2/trunk@14773 d0ab736e-dc22-4aeb-8dc9-08def0aa14fd