\selectlanguage now also accepts a
control sequence as its argument. This was included to provide
compatibility for users who were used to the syntax of the original
german.tex, but wanted to switch to babel. The escape
character is `peeled off' and the name of the control sequence is then
used as the name of the language to select.
Another change to the \selectlanguage macro is that it now
stores the name of the current language in the control sequence
\languagename. The contents of this control sequence could be
tested in the following way:
\edef\tmp{\string english}
\ifx\languagename\tmp
...
\else
...
\fi
The construction with \string is necessary because
\languagename returns the name with characters of category code
12 (other).