3.0.3 (stable)

Build:
* docs/docs/reference/meson.build: Check if perl is found
  (Kjell Ahlstedt) Issue #53 (Rasmus Thomsen)
* README.md: Describe building with Meson
  (Kjell Ahlstedt)

Examples:
* Add example of using libsigc++ with Qt
  (Robert Middleton) Pull request #35

Tests:
* Replace C-style casts with static_cast<>
  (Lennard Berger)