default (and later optional) STIG ID sequence and split and merge pattern

[ejaronne]

To allow more room for multiple rules kept together for one SRG rule:

Instead of ZZZZ-00-000001, ZZZZ-00-000002, ZZZZ-00-000003

default "padding" by tens (first release of feature) ZZZZ-00-000010, ZZZZ-00-000020, ZZZZ-00-000030

later, allow the user to specify the padding value at project creation