Add two more fields to DlgPrefLV2: the number of checked parameters and the current plugin's id
Set the number of checked parameters to 0 when changing the plugin.
Modify dlgpreflv2dlg.ui'
Implement the logic for restricting the user to select up to 8 active parameters
Rename the layout from lv2_vertical_layout_right to lv2_vertical_layout_params
Add information about active button parameters inside EffectManifest
Display and update button parameters too inside LV2 preferences
Update slotApply() to treat button parameters too
Connect clicked() signal to slotDisplayButtonParameters()
Use the mapping provided by the EffectManifest when asking for a button parameter