Names of ClassDB-bound methods changed

[jmf]

Operating system or device - Godot version:
Linux 4.11
Godot master e883cda

Issue description:
Some bound methods were renamed in 3.0. This brings issues, when those methods are called from C++ code. This is an example from scene/gui/tree.cpp:
v_scroll->call_deferred("set_val", ofs - screenh + h);
It fails (silently) because "set_val" was renamed into "set_value" in 3.0.

This probably happens in other files, too. Checking all occurrences of call_deferred() and related functions that call bound methods will be necessary.
Also displaying an error when a call fails would make debugging easier.

The example above is the cause for a bug, where trees don't scroll when using the arrow-down key to navigate.

[akien-mga]

That's typically something that any contributor could do by grepping for call_deferred and checking manually all of them. Have fun :)

[reduz]

that was the only one in all the source code..