Zabbix

A.F....... [ZBXNEXT-1675] changes:
- re-factored code in DRule and HttpTest APIs, so that parser initialization is outside loops;
- added update interval, history and trend validation in ItemGeneral;
- added 'lldmacro' option for FlexibleIntervalParser and UpdateIntervalParser;
- added 'suffixes' option for SimpleIntervalParser;
- added several default time values with suffixes in defines;
- added option to sort item subfilter by another value;
- integrated time suffix and macro support in item edit form, item list and item massupdate form;
- a time taht is 0, now returns 0s by default.