* Fix SQL injection in history delete on the sqlite backend
Also, return a value from history delete on the sqlite backend. Otherwise the
command always responded with "Deleted None entries from history".
Also, use XH_SQLITE_TABLE_NAME consistently across xonsh.history.sqlite.
Before, most of the calls used the variable, but part of them hard-coded the
table name.
* Add news entry
* Fix ReST syntax in changelog entry
