[Feature] Stacking filters

[stelzo]

Parameter to stack multiple filters behind each other. Example:

<param name="filters" type="string" value="voxel_0,aabb_0"/>
<param name="aabb_0_invert" type="bool" value="true"/>

First applies a Voxel Downsampling filter followed by the AABB in inverted mode.
The _0 implies the first instance which can be used to set specific parameters with a prefix.