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[tothtamas28]

• Change function add_backets to use bottom_up. This fixes an issue where the function does not recur on the items of a KSequence.
• Add an artificial default bracket production. In case a term would require parentheses but there's no bracket production for its sort, this symbol will be applied. This emulates the following parametric production from module KSEQ:

  syntax {Sort} Sort ::= "(" Sort ")" [bracket, group(defaultBracket), applyPriority(1)]