Add psql native funstions 'point' and 'polygon'

Author: kimakan

src/queryparser/postgresql/PostgreSQLLexer.g4

@@ -130,6 +130,8 @@ OUTER				: O_ U_ T_ E_ R_  ;
 PARTITION_SYM		: P_ A_ R_ T_ I_ T_ I_ O_ N_  ;
 PDIST               : P_ D_ I_ S_ T_ ;
 PI				    : P_ I_  ;
+POINT				  : P_ O_ I_ N_ T_ ;
+POLYGON				: P_ O_ L_ Y_ G_ O_ N_ ;
 POSITION_SYM        : P_ O_ S_ I_ T_ I_ O_ N_ ;
 POW				    : P_ O_ W_  ;
 POWER				: P_ O_ W_ E_ R_  ;

src/queryparser/postgresql/PostgreSQLParser.g4

@@ -243,7 +243,8 @@ pg_sphere_op:
     | SNOTOVERLAP ;
 
 sbit_expr:
-      ( pg_sphere_object | spoint )
+      ( polygon pg_sphere_op point )
+    | ( pg_sphere_object | spoint )
     | ( ( spoint | simple_expr ) pg_sphere_op pg_sphere_object)
     | ( pg_sphere_object EQ pg_sphere_object )
     | ( pg_sphere_object pg_sphere_op pg_sphere_object )
@@ -255,6 +256,8 @@ sbit_expr:
     | ( ( spoint | scircle | sline | sellipse | spoly | spath | simple_expr ) ( ( PLUS | MINUS )? strans )+ ) ;
 
 
+polygon:                POLYGON string_literal ;
+point:                  POINT LPAREN bit_expr COMMA bit_expr RPAREN ;
 spoint:                 SPOINT LPAREN bit_expr COMMA bit_expr RPAREN ;
 scircle:                SCIRCLE LPAREN spoint COMMA bit_expr RPAREN ;
 sline:                  ( SLINE LPAREN spoint COMMA spoint RPAREN ) | ( SLINE LPAREN strans COMMA bit_expr RPAREN );