Initial support for grid stitching from paths

[zeb]

This PR is a preliminary work towards the stitching use case described in imagej/imagej-omero#45.

The intent would be to enable file lookup from a list of absolute paths in arbitrary directories (such as the OMERO ManagedRepository), without duplication to a temporary location beforehand and with moderate refactoring impact on the plugin. Ideally, all grid types exposed in the plugin would be candidates for such support, but the current patch is restricted to a minimal subset in order to get a prototype running and gather early feedback on this approach.

The current behaviour is as follows:

• limited to Unknown positions and Sequential Images grid types
• lookup the paths to tiles from a TilePath.txt file:
  • the file may be located within the same directory as TileConfiguration.txt or elsewhere (side note: paths read from/written to TileConfiguration.txt are currently unchanged)
  • the file content is expected to be a list of absolute paths (one per line - comments (#), empty lines and relative paths are ignored) - eg.

# Ignore the first three lines
ignore_relative_path.tif

/path/to/tile_1.tif
/path/to/tile_i.tif

[ctrueden]

@zeb Awesome! I'll try to review this in detail early next week, unless @StephanPreibisch gets to it first.

[zeb]

This request was probably too hasty - on second thought, a more manageable approach might just be to maintain a separate plugin/adapter without altering upstream. Closing, sorry for the noise.