SILENTLY CONVERT NULL

In-Place in InnoDB do not convert from NULL to NOT NULL
due to loss of information, it will always give an error
for such rows.

But ALGORITHM = COPY will do such conversion with only
a warning (which in case of strict sql_mode it will turn the
warning to an error).

So to be consistent, we will only allow INPLACE for
NULL -> NOT NULL under strict sql_mode, since that will give
an error for both INPLACE and COPY.

If not strict mode ha_innodbase::check_if_supported_inplace_alter
will return failure, and depending on ALGORITHM it will fall back to
COPY or fail.

Also notice that ADD PRIMARY KEY () will implicitly add NOT NULL if
not already there!

Updated tests that uses INPLACE by setting strict sql_mode.

Also updated some Swedish error messages.

rb 1679 approved by marko.