fixed _ArrayCat error

[chris75vie]

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ERROR: Primitive '_ArrayCat' failed.
Wrong type.
RECEIVER:
Instance of String {    (0x1131eee40, gc=01, fmt=07, flg=11, set=02)
  indexed slots [3]
      0 : -
      1 : >
      2 :  
}
CALL STACK:
	MethodError:reportError
		arg this = <instance of PrimitiveFailedError>
	Nil:handleError
		arg this = nil
		arg error = <instance of PrimitiveFailedError>
	Thread:handleError
		arg this = <instance of Thread>
		arg error = <instance of PrimitiveFailedError>
	Object:throw
		arg this = <instance of PrimitiveFailedError>
	Object:primitiveFailed
		arg this = "-> "
	Interpreter:interpretPrintCmdLine
		arg this = <instance of Interpreter>
		var res = <instance of HarmonicMetricCS>
		var func = <instance of Function>
		var code = "x = HarmonicMetricCS.new;"
		var doc = nil
		var ideClass = <instance of Meta_ScIDE>
	Process:interpretPrintCmdLine
		arg this = <instance of Main>
^^ The preceding error dump is for ERROR: Primitive '_ArrayCat' failed.
Wrong type.
RECEIVER: -> 

[chris75vie]

the second commits removes the factorial implementation to avoid

WARNING: Extension in '~/Library/Application Support/SuperCollider/downloaded-quarks/DissonanceLib/classes/numberExtras.sc' overwrites SimpleNumber:factorial in main class library.
Intentional overwrites must be put in a 'SystemOverwrites' subfolder.