Readlif

- Bugfix: Fix error in mosaic parsing. `PosX` metadata was incorrectly read from `PosY`
- Thanks to jojoelfe for the PR!

- Bugfix: switch from `io.BufferedIOBase` to `io.IOBase`

- Added support for loading files from buffers
- Thans to PR from JacksonMaxfield

Fixed documentation issue, now correctly indicates unites of `LifImage.scale` as px/µm

- Added support for tiled images
- `m` was added as a new dimension (for tiled images)
- `LifImage` changes:
- New `get_iter_m()` function
- New `mosaic_position` attribute with `(FieldX, FieldY, PosX, PosY)`
- Under the hood changes
- `LifImage.dims` is now a named tuple for clearer code
- Other things
- Prettier outputs for `repr()`
- Switch to github CI with help from jidicula

Added NotImplementedError for tiled images until the feature can be added