Minor Quantlab release 3.1.4114

4114:

* qlab: Compiler crash on sort(vector(non-tuple)).

* qlab: Code gen bug with generated vectors of size 0.

* qlab: Missing null check in zero_brent().

+ qlab: Named index variable in range-for a la 'for (a : v1, b : v2 ; ix) {...'

+ qlab: qlc.clone_object().

+ qlab: json.{print,get_object}() support for set_* (<-> array).

+ qlab: Support for exclusive percentiles in stat functions.

+ dev_ui: Auto-save for 'quantlab -L'.

* dev_ui: Auto-save setting was not persistent.

~ dev_ui: Auto-save defaults to on.

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