Log Message:
Update opensp to 1.5.1.

Changes:

Enable run time selection of message format with SP_MESSAGE_FORMAT
environment variable. Value is one of XML, NONE, TRADITIONAL.

When validating/parseing a document using http, OpenSP will now follow
any redirects headers/requests from the server.

The environment variable SP_HTTP_USER_AGENT can be used to specify a
UserAgent: header.

The environment variable SP_HTTP_ACCEPT can be used to specify Accept:
headers.

A number of enhancements have been made to the osx tool: security
fixes in the handling of output files; addition of the "preserve case
option".

A testing framework together with some initial tests have been
added. Currently there are 22 tests. 6 of which fail.

Support for Mac OS/X, Darwin has been improved. Build infrastructure
and localisation fixes and enhancements. Improved compiler support.