Release v0.12.15

• implement ltrim, rtrim, and trim functions
• implement gojq.ParseError for getting the offset and token of query parsing error
• implement gojq.HaltError for detecting halt errors and stopping outer iteration
• fix object construction with duplicate keys ({x:0,y:1} | {a:.x,a:.y})
• fix halt and halt_error functions to stop the command execution immediately
• fix variable scope of binding syntax ("a" as $v | def f: $v; "b" as $v | f)
• fix pre-defined variables to be available in initial modules ($ARGS in ~/.jq)
• fix ltrimstr and rtrimstr functions to emit error on non-string input
• fix nearbyint and rint functions to round ties to even
• improve parser to allow reduce, foreach, if, try-catch syntax as object values
• remove pow10 in favor of exp10, define scalbn and scalbln by ldexp