added log query expression support (removed bnf based parsers)
added 'eval' command (create new field by evaluating
specified expression)
added avg, first, last, max, min, and range aggregation functions
logdb code refactoring
 * added <, <=, >, >=, ==, !=, and, or operators to expression
 * added if, case expression
added string constant and concat function to expression
added string manupulation funcs (len, left, right, substr, trim)
added type conversion funcs (date, int, long, string)
removed system.out
added isnotnull, isnull, isnum, isstr, match function
support search expression and wildcard match
added rex command
Merge branch 'new-logquery-parser'