RT_Util Refactoring

[jdcrensh]

Some refactoring should be done for RT_Util and RT_UtilTest. Over time, it's become a somewhat bloated static utility class. Breaking the methods out into multiple classes named for the responsibilities they perform would ease maintenance and make the API easier to use. The challenge would be minimizing the quantity of new utility classes so that they don't end up being too small.

RT_BooleanUtil: Booleans
RT_CollectionUtil: Lists, Sets, Maps
RT_DateUtil: Dates
RT_NumberUtil: Integers, Decimals
RT_PagesUtil: Picklists, Messages
RT_SchemaUtil: Describes, Query building, DML
RT_StringUtil: Strings
RT_SystemUtil: Trigger utils, Limits, Stopwatch, equals/hashCode, logging