Log Message:
Update to 0.15:

     Fifteenth alpha version, released on 2004/02/04.

     o   Finally dropped bt_make and bt_wrap, together with all compatibility
         code introduced around them.

     o   M4 is no longer needed.  It was introduced to clean up code, but it
         has proven to only ofuscate it.  As a side effect, bt_swcgen uses
         shell scripts instead of macro files to generate system wide configu-
         ration.

     o   Added some checks to bt_config: bt_check_hdr_time(),
         bt_check_prog_cc_flag() and bt_check_prog_cxx_flag().

     o   Support for the `+=' operator (append text to a variable) was added
         to bt_sh.  This can be used to simplify syntax when writting scripts.

     o   Support for pkgconfig files was added to bt_pkgflags.

     o   Support for pkgconfig command line syntax was added to bt_pkgflags
         (it is not exactly the same, but we now support operators in their
         real form, like `=' or `!=', plus spaces to separate keywords).

     o   Multiple portability problems fixed.