Improved formula validation to mark nested if statements as invalid. They are unsupported, but would show as valid.
Fixed formula validation issues with modifiers in merge tags containing underscores (such as {:1:choice_label}).
Added PHP version of gpac_should_clean_merge_tag_value.
Fixed issue where setting gpac_should_clean_merge_tag_value would not always ensure that non-numeric values are quoted.
Fixed regression concerning using product prices in formulas
Fixed issue with conditional logic where empty strings inside conditions could create odd results on initial load. Additionally, comparisons between numbers and non-numeric strings has been made more consistent.
