add some big improvements to parse error messages

change the parser to not attempt to parse the elements following
'from' unless there is a actual 'from'
improve the symbol parser to try to deal with issues when symbols are
  next to eachother with no intervening whitespaces
improve number literal parsing to fail if there are trailing letters
  or digits which aren't part of the number and aren't separated with
  whitespace
add some code to start analysing the quality of parse error messages

tools/Language/SQL/SimpleSQL/Postgres.lhs

@@ -264,6 +264,8 @@ select page reference
 
 >     ,"SELECT 2+2;"
 
->     ,"SELECT distributors.* WHERE distributors.name = 'Westward';"
+>     -- simple-sql-parser doesn't support where without from
+>     -- this can be added for the postgres dialect when it is written
+>     --,"SELECT distributors.* WHERE distributors.name = 'Westward';"
 
 >     ]