Reduce or eliminate output when used via cli

[wltjr]

When I run etui via cli, it seems to constantly output information when navigating the PDF documents etc. Likely for debug or something. But not sure users should see this stuff in general. Maybe add a -d/--debug flag, or something with log level so its only outputted when desired for development, etc. Thanks!

etui docs/manual.pdf
 $$$$ etui_object_add : 0x4000000391e6
 pre 0 $$ 612x792
 pre 1 $$ 612x792
 pre 2 $$ 612x792
 _etui_smart_resize 2 : 612x792
 $$$$ _etui_smart_resize_cb : data: 0x4000000391e6   obj: 0x4000000395e7  612x792
 pre 3 $$ 612x792
focus in
 end $$ 612x792
 pre 0 $$ 612x792
 pre 1 $$ 612x792
 pre 2 $$ 612x792
 pre 3 $$ 612x792
 end $$ 612x792
 pre 0 $$ 612x792
 pre 1 $$ 612x792
 pre 2 $$ 612x792
 pre 3 $$ 612x792
 end $$ 612x792
 pre 0 $$ 612x792
 pre 1 $$ 612x792
 pre 2 $$ 612x792
 pre 3 $$ 612x792
 end $$ 612x792
 pre 0 $$ 612x792
 pre 1 $$ 612x792
 pre 2 $$ 612x792
 pre 3 $$ 612x792
 end $$ 612x792
 pre 0 $$ 612x792
 pre 1 $$ 612x792
 pre 2 $$ 612x792
 pre 3 $$ 612x792
 end $$ 612x792
focus out

[vtorri]

there is an improvement which is currently done, hence this annoying ouput. In the end, it will be removed