2.10.4 (stable)

Build:
* Meson build: Set default value of the 'warnings' option to 'min'
  (Kjell Ahlstedt)
* NMake Makefiles: Several improvements
  (Chun-Wei Fan) Pull request #58
* docs/reference/: Update for Doxygen >= 1.8.16
  (Kjell Ahlstedt)

Documentation:
* docs/manual/libsigc_manual.xml: Update signal and slot syntax
  (Kjell Ahlstedt) Issue #59 (Denis Washington)

The tarball for 2.10.4 has been created with 'meson dist'.
If you build with Autotools from the tarball, please read the relevant
part of README.