The locale macros `\thesis@<locale>@winter` and `\thesis@<locale>@summer`

were renamed to `\thesis@<locale>@spring` and `\thesis@<locale>@fall`.

The semantics have also changed. The `\thesis@parseDate` macro no
longer sets `\thesis@season` to `winter` if `\thesis@month` < 7 and to
`summer` otherwise. Instead, the `\thesis@season` macro is set to
`spring` if 2 > `\thesis@month` < 9 and to `fall` otherwise.

The `\thesis@academicYear` macro is no longer set to
`\thesis@year`-1/`\thesis@year` if `\thesis@month` < 7 and to
`\thesis@year`/`\thesis@year`+1 otherwise. Instead, the
`\thesis@academicYear` macro is set to
`\thesis@year`-1/`\thesis@year` if `\thesis@month` < 9 and to
`\thesis@year`/`\thesis@year`+1 otherwise.

These changed month ranges reflect more accurately the beginning and the
end of the spring and fall semesters.