Added KEY_BLOCK_SIZE option to I_S.TABLES.CREATE_OPTIONS field

Bug#37671 crash on prepared statement + cursor + geometry + too many open files!
if mysql_execute_command() returns error then free materialized_cursor object.
is_rnd_inited is added to satisfy rnd_end() assertion
(handler may be uninitialized in some cases)

Removed values with more than 15 significant digits from the test case. Results of 
reading/printing such values using system library functions depend on implementation 
and thus are not portable.

Problem:
 XML syntax parser allowed to use quoted strings as attribute names,
 and tried to put them into parser state stack instead of identifiers.
 After that parser failed, if quoted string contained some slash characters.
Fix:
 - Disallowing quoted strings in regular tags.
 - Allowing quoted string in DOCTYPE declararion, but
 don't push it into parse state stack (just skip it).

Field_varstring::store
      
The code that temporary saved the bitmaps of the read set and the write set so that
it can set it to all columns for debug purposes was not expecting that the
table->read_set and table->write_set can be the same. And was always saving both in 
sequence.
As a result the original value was never restored.
Fixed by saving & restoring the original value only once if the two sets are the
same (in a special set of functions).

no conflicts

if table has bit fields then uneven bits(if exist) are stored into null bits place.
So we need to copy null bits in case of uneven bit field presence.

added ability for TINY[MEDIUM] text fields 
to be converted to greater subtype during
alter if necessary(altered charset)