Stitching: add ignore stage Z option

For multi_series_file and grid stitching, this flag, when enabled, will
force all Z stacks to be treated as though their stage position was 0,
effectively aligning them.

This option can help resolve issues stitching datasets that were
acquired in a cascade from an origin point.
Stitching plugin - fusion: report status

The fusion operation of the stitching plugin now displays a status bar for each
block being fused, and reports the overall status (current C, T slice being
fused).
Merge branch 'stitching-status'

Adds status reporting to the stitcher's fusion operations.
Merge branch 'ignore-z-stage'

Adds a flag for grid and multi-series stitching to ignore Z stage coordinates,
aligning everything to 0.