Choose the major mode for this buffer automatically.
Also sets up any specified local variables of the file.
Uses the visited file name, the -*- line, and the local variables spec.
This function is called automatically from `find-file'. In that case,
we may set up the file-specified mode and local variables,
depending on the value of `enable-local-variables'.
In addition, if `local-enable-local-variables' is nil, we do
not set local variables (though we do notice a mode specified with -*-.)
`enable-local-variables' is ignored if you run `normal-mode' interactively,
or from Lisp without specifying the optional argument FIND-FILE;
in that case, this function acts as if `enable-local-variables' were t.