Version 10.6.0

• Added support for reading and writing the unique ID of P6 user defined fields via new getUniqueID and setUniqueID methods on `CustomField (based on a suggestion by Wes Lund).
• Added support for reading and writing scope, scope ID, and sequence number attributes for activity codes (based on a suggestion by Wes Lund).
• Added support for reading and writing sequence number and color attributes for activity code values (based on a suggestion by Wes Lund).
• Added isWorking method to ProjectCalendarException to make it clearer how to determine if the exception changes the dates it is applied to into working or non-working days.
• Improve reading task start from certain Planner files.
• Improve reading predecessor lag values from Planner files.
• Ensure calendar hierarchy is written correctly to Planner files.
• Don't write null tasks to Planner files as Planner will not read files which contain them.
• When writing Planner file, ignore constrainyt types which Planer can't represent.
• Don't write emply predecessor lists to Planner files.
• Improve handling of lag duration when writing Planner files.
• Improve ProjectCalendar start date calculation when we have long runs of non-working days.
• Performance enhancement for timephased data normalisation.