base sqlite on postgres, instead of mysql. throw errors for unsupported features.

lib/dialect/sqlite.js

@@ -7,13 +7,36 @@ var Sqlite = function() {
   this.params = [];
 };
 
-util.inherits(Sqlite, require(__dirname + '/mysql'));
+util.inherits(Sqlite, require(__dirname + '/postgres'));
 
-Sqlite.prototype._quoteCharacter = '"';
+Sqlite.prototype._arrayAggFunctionName = 'GROUP_CONCAT';
+
+Sqlite.prototype.visitDefault = function(parameter) {
+  throw new Error('SQLite requires that all rows of a multi-row insert are for the same columns.');
+};
+
+Sqlite.prototype.visitOrderByColumn = function(column) {
+  if(column.direction) {
+    return this.visit(column.column) + ' ' + this.visit(column.direction);
+  } else {
+    return this.visit(column.column);
+  }
+};
+
+Sqlite.prototype.visitDropColumn = function(dropColumn) {
+  throw new Error('SQLite does not allow dropping columns.');
+};
 
 Sqlite.prototype.visitRenameColumn = function(renameColumn) {
-  throw new Error('SQLite does not allow renaming columns');
+  throw new Error('SQLite does not allow renaming columns.');
+};
+
+Sqlite.prototype.visitIfExists = function() {
+  throw new Error('SQLite does not support IF EXISTS.');
 };
 
+Sqlite.prototype.visitIfNotExists = function() {
+  throw new Error('SQLite does not support IF NOT EXISTS.');
+};
 
 module.exports = Sqlite;