Fix warnings qt3support

[guitorri]

Closes #656.

[felix-salfelder]

truly awesome. please merge (regardless of micro-regressions).

[guitorri]

For some reason some deprecated constructor warning are not showing on my system (they show up on Windows and Linux builds).
Using -DQT_DEPRECATED_WARNINGS seems to do the trick. I will push more fixes shortly.

[guitorri]

Rebased, reverted the regression on pressing Esc. Silenced a few more warnings.
There are a few still warnings remaining. I will try to clear them tomorrow.

[guitorri]

still a few things to fix

[guitorri]

All warnings should be fixed. Shall we enable -Werror from now on?
I believe I tested everything. Please take a look.

[guitorri]

Bump.
I think we should merge this before we start merging new features.

[in3otd]

lemme do a last check 😁
About enabling -Werror I'm not sure but we could try and revert in case we don't like it...

[in3otd]

...it seems clang++ on Travis (linux) does not like some Qt4 stuff and emits some warnings (?)

[guitorri]

I am afraid there is not much we can do about these warnings. Qt4 is no longer supported on that version of OSX/Clang. I will try to have a look, if I find a fix I will let you know in another PR. 😄

[in3otd]

I think I saw the warnings for the Qt4 in Linux actually... (but I do not see them here locally)

Instead, I just saw here I have also

graphictextdialog.cpp:34:67: warning: unused parameter 'name' [-Wunused-parameter]
savedialog.cpp:34:65: warning: unused parameter 'modal' [-Wunused-parameter]

besides a ton of clang-3.8: warning: -ldl: 'linker' input unused (as usual here), which is maybe just due to the not up-to-date `clang (?)

I'm starting to think that enabling -Werror is maybe too much...

[felix-salfelder]

-Werror is too much as a default build option (with or without debugging) simply because future compilers might warn about stuff that we cannot know yet.

yet, it might be pretty useful so set -Werror for CI, at least until we hit a warning that we absolutely do not agree with (or have no clue whatsoever). make CXXFLAGS=-Werror ...

[guitorri]

Right, we are not ready for -Werror. Even for CI it would create too much noise at this stage. Perhaps before a release we can make some sanitation until we see things are more or less under control.
I thing the solution to warning: -ldl: 'linker' input unused is to not pass the flag everywhere.
The warning: unused parameter are not Qt3Support issues. We should open another issue.

[in3otd]

yeah, as usual noticed a small issue just after merging: when opening a project I get a message on the console

Warning: QLayout: Attempting to add QLayout "" to SaveDialog "", which already has a layout

everything seems to work, anyway.