Bug #15890 Partitions: Strange interpretation of partition number

Description:
There are several unfortunate effects arount the checks of 
assigned partition numbers:
1. CREATE TABLE t1 ( f1 BIGINT, f2 char(20))
    PARTITION BY HASH(f1) PARTITIONS -1;
     --> ERROR 42000: You have an error in your SQL syntax; check the 
           manual ..... for the right syntax to use near '-1' at line 2
    I think the error message
           ERROR HY000: Number of partitions = -1 is not an allowed value
    would be better.
2. CREATE TABLE t1 ( f1 BIGINT, f2 char(20))
    PARTITION BY HASH(f1) PARTITIONS 1.5;
    SHOW CREATE TABLE t1;
    Table   Create Table
    t1      CREATE TABLE `t1` (
      `f1` bigint(20) default NULL,
      `f2` char(20) default NULL
    ) ENGINE=MyISAM DEFAULT CHARSET=latin1 PARTITION BY HASH (f1)
    PARTITIONS 1
    I think the brutal rounding/truncating of 1.5 to 1 (decrease value 33 %)
    is not acceptable. An error message would be better.
3. CREATE TABLE t1 ( f1 BIGINT, f2 char(20))
    PARTITION BY HASH(f1) PARTITIONS 0.2E+1;
    --> ERROR HY000: Number of partitions = 0 is not an allowed value
    In mathematics 0.2E+1 equals 2, why shouldn't this be also
    valid as long a (double) float value can be converted to an integer
    without rounding.
4. CREATE TABLE t1 ( f1 BIGINT, f2 char(20))
    PARTITION BY HASH(f1) PARTITIONS 1E+300;
    SHOW CREATE TABLE t1;
    Table   Create Table
     t1      CREATE TABLE `t1` (
       `f1` bigint(20) default NULL,
       `f2` char(20) default NULL
      ) ENGINE=MyISAM DEFAULT CHARSET=latin1 
      PARTITION BY HASH (f1) PARTITIONS 1
    Effect similar bad like 3.

My environment:
   - Intel PC with Linux(SuSE 9.3)
   - MySQL compiled from source
         bk-internal.mysql.com:/home/bk/mysql-5.1-wl2604-new
              last ChangeSet@1.1981, 2005-12-15   
         and also
         Version 5.1
              last ChangeSet@1.1967.3.2, 2005-12-16   

How to repeat:
Please execute the statements above.

Suggested fix:
Please implement a strict behaviour.
- The assigned partition/subpartion number must
  consist of digits without leading zeros and 
  nothing else (no fractions, no exponents).
- I like that numbers enclosed between single
  or double quotes are rejected. Such values 
  are strings and not a number.

A more non strict behaviour like accept all
values written in integer/decimal/floating point style
which can be converted (without rounding/truncating)
to an integer is thinkable, but I do not beleave that
such a feature gives any worth-while benefits.

This is a general problem and I fixed a solution that can
hopefully be reused by others as well.

Was reviewed by Antony Curtis with comments to
1) Add comments to new rules
2) Change name of new rules to only_ulong_num instead of
real_ulong_num

fixed in 5.1-kt tree

Patch will appear in 5.1.12

Documented in 5.1.12 changelog. Also updated Partitioning and CREATE TABLE/ALTER TABLE material in 5.1 Manual.