Add interface+stub for logging an array of strings
Add implementation for ws_log_ary()
Add helper macros for converting int to string in source
Add to-string functionality for ws_value_union type
Rewrite func_log()

This patch completely rewrites the func_log() function to be able to
parse ws_value_* types into their string representation and log them.

Pair-programmed-with: Marcel Müller <com2040@gmail.com>
Suggested-by: Marcel Müller <com2040@gmail.com>
Merge pull request #548 from matthiasbeyer/add-logging_support

Rewrite func_log()
Removed unused member of internal compositor context
Fixed ws_object_cmp if the same pointers are passed in
Fixed uuid generation for ws_wayland_obj
Added ws_buffer_blit_at
Moved buffer_blit implementation to use the blit_at method
Added impl for ws_buffer_clear
Added width, height, x, and y to abstract_shell
Added stubs for compositing_events to ws_compositor
Added stubs for monitor double buffering
Added fields for monitor double buffering
Added creation of two buffers for ws_monitor
Added ws_monitor_get_active_buffer
Added impl of ws_monitor_flip_buffers
Added impl for ws_monitor_set_fb