[sigc] Deprecated libsigc++ lambda expressions, sigc::group() and sigc::var()

[Kjell Ahlstedt <kjell ahlstedt bredband net>]

I have pushed to the git repository a patch that deprecates libsigc++ 
lambda expressions and everything that depends on them, which is 
basically sigc::group() and sigc::var(). This functionality will most 
probably be deprecated in future releases of libsigc++. It duplicates 
the functionality of C++11 lambda expressions.

This is the first deprecation in libsigc++, so some general information 
about deprecation might be useful.

Don't panic, if you use deprecated functionality. You won't notice any 
difference unless you define the preprocessor macro 
SIGCXX_DISABLE_DEPRECATED when you compile your program or function 
library. If you do define it, and you use any deprecated functionality, 
the compiler will report errors.
Bugs concerning deprecated functionality are less likely to be fixed 
than other bugs.
In the next major release, libsigc++ 3.0 (whenever that will be), 
deprecated functionality may be deleted.

Kjell Ahlstedt