Split spine labels between the alpha and numeric part of the LC subclass

Split spine labels between the alpha and numeric part of the LC subclass

Some sites jam the alpha and numberic parts of the LC subclass together;
for example "QA76.76" instead of "QA 76.76". Without the space, Evergreen
was not inserting a line break. This commit will insert a line break
automatically if the first element of a call number contains 1 to 3 alpha
characters followed immediately by 1 or more numbers.

This should not affect Dewey or most other classification systems, but will
have the effect of making call numbers split as follows:

Given "QA76.76 S93 1998", generate:

QA
76.76
S93
1998

git-svn-id: svn://svn.open-ils.org/ILS/trunk@17359 dcc99617-32d9-48b4-a31d-7c20da2025e4