Release v0.9.0

• implement various functions (infinite, isfinite, isinfinite, finites, isnormal, normals)
• implement environment variables loader as a compiler option
• implement $NAME::NAME syntax for imported JSON variable
• fix modify operator with empty against array ([range(9)] | (.[] | select(. % 2 > 0)) |= empty)
• fix variable and function scopes ({ x: 1 } | . as $x | (.x as $x | $x) | ., $x)
• fix path analyzer
• fix type check in startswith and endswith
• ignore type error of ltrimstr and rtrimstr
• remove nano seconds from mktime output
• trim newline at the end of error messages
• improve documents and examples