WL#648: SHOW TABLE STATUS to show temporary tables

Currently temporary tables are invisible for SHOW TABLES,
SHOW OPEN TABLES, SHOW TABLE STATUS, and within INFORMATION_SCHEMA.

Also there is no way to see which tables are now hidden, replaced by temporary 
tables. 

This should be fixed by adding a new column 'Temporary' to the above results that 
should contain 1 for temporary tables and 0 otherwise. (Or 'YES'/'NO'.)

Temporary tables for the user should be added to all results.

This is in line with the fact that in 5.x we will allow one to do

SHOW [column list] TABLE STATUS where temporary=1;

SHOW COLUMNS FROM .. (or DESCRIBE) is another statement from which temporary 
tables are hidden. (This is BUG#12770.)

Feature request:
BUG#20001 Support for temp-tables in INFORMATION_SCHEMA