v3.0.0

This release finally brings ext-session-lock-v1 support! Gtklock is now safer and works on many more compositors.
Huge thanks to @Cu3PO42 for their work on the gtk-session-lock library.

Other changes include:

• Switched from make to meson (Thank you @lujianhua)
• Added --layout option for loading custom XML layout files (Thank you @Lassebq for the suggestion)