implemented and test-covered computeLeq and computeGeq for Value
fixed comment
changed AttributeSchema name pattern to ColumnSchema (including method etc.). implemented methods to handle set<uint8_t> in BinarySerializer. modified Relation-, Column-, and IndexSchema: IndexSchema now support multiple columns. Removed primaryKey attribute from RelationSchema because it can be determined via indexSchemas and notNull attribute. Implemented indexSchemaType as enum. IndexSchema now support unique and non unique-indices
removed commented and non longer used attributes
implemented global register in operator
merged bugs
code clean up
added query results