Installing FocusStack

1. Check out the latest main branch from the repository, or download a release checkpoint.
2. Use pathtool from within Matlab to add the main directory to the Matlab path.
3. (Optional but recommended) MappedTensor (a low-level component of FocusStack) includes several accelerated functions written in C. These functions require mex to be correctly configured on your machine, and will be compiled automatically when needed. If mex is not configured, then much slower Matlab equivalents will be used.