Refactoring of arbiter to add flexibility and to allow reuse kernels

This is major refactoring of arbiter in order improve the use of kernels and simplify them.

Features:

• run multiple kernels
• partial selection masks
• expression with selection, including expression for final selection
• reduction instruction for group matcher based on selection masks
• output schema update in kernels

@hammerd

docs/devices.md

@@ -50,15 +50,13 @@ Therefore, settings related to how this is done should typically be managed via
 The parameters seen in the "Preview" box on the manager overview scene control:
 
 - How to select which frame to preview (for non-negative indices)
-    - See [Index selection mode](schemas/BaseCorrection.md#preview.selectionMode)
 	- Frame can be extracted directly from image ndarray (`frame` mode), by looking up corresponding frame in cell table (`cell` mode), or by looking up in pulse table (`pulse` mode)
     - For XTDF detectors, the mapping tables are typically `image.cellId` and `image.pulseId`.
 	  Which selection mode makes sense depends on detector, veto pattern, and experimental setup.
     - If the specified cell or pulse is not found in the respective table, a warning is issued and the first frame is sent instead.
 - Which frame or statistic to send
-    - See [Index for preview](schemas/BaseCorrection.md#preview.index)
     - If the index is non-negative, a single frame is sliced from the image data.
-	  How this frame is found depends on the the [index selection mode](schemas/BaseCorrection.md#preview.selectionMode).
+	  How this frame is found depends on the the index selection mode (previous point).
     - If the index is negative, a statistic is computed across all frames for a summary preview.
       Note that this is done individually per pixel and that `NaN` values are ignored.
       Options are: