Enhance boolean search expression.

This patch changes two things:
1) When using custom Tokenizer, enables searching for UUIDs, product names and other items with dashes in their names by counting only space and dash character as an expression instead of just dash (see:
teamtnt#161, teamtnt#215, trilbymedia/grav-plugin-tntsearch#92)
2) In some sense it partialy reverts teamtnt@33cc524 as email address parts are broken into tokens in the default Tokenizer anyway.

src/Support/Expression.php

@@ -86,8 +86,8 @@ public function priority($operator)
 
     public function lex($string)
     {
-        $bad  = [' or ', '-', ' ', '@', '.'];
-        $good = [ '|'  , '~', '&', '&', '&'];
+        $bad  = [' or ', ' -', ' '];
+        $good = [ '|'  , '~', '&'];
 
         $string = str_replace($bad, $good, $string);
         $string = mb_strtolower($string);

tests/support/ExpressionTest.php

@@ -15,7 +15,6 @@ public function testToPostfix()
         $this->assertEquals(['great', 'awsome', '|'], $exp->toPostfix("great or awsome"));
         $this->assertEquals(['great', 'awsome', '&'], $exp->toPostfix("great awsome"));
         $this->assertEquals(['email', 'test', '&', 'com', '&'], $exp->toPostfix("email test com"));
-        $this->assertEquals(['email', 'test', '&', 'com', '&'], $exp->toPostfix("[email protected]"));
         $this->assertEquals(['first', 'last', '&', 'something', 'else', '&', '|'], $exp->toPostfix("(first last) or (something else)"));
     }
 }