Fixes this warning raised by Travis CI on macOS:
```
editor/plugins/polygon_2d_editor_plugin.cpp:95:6: warning: variable 'skeleton' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
if (!node->has_node(node->get_skeleton())) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
editor/plugins/polygon_2d_editor_plugin.cpp:106:7: note: uninitialized use occurs here
if (!skeleton) {
^~~~~~~~
editor/plugins/polygon_2d_editor_plugin.cpp:95:2: note: remove the 'if' if its condition is always false
if (!node->has_node(node->get_skeleton())) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
editor/plugins/polygon_2d_editor_plugin.cpp:94:22: note: initialize the variable 'skeleton' to silence this warning
Skeleton2D *skeleton;
^
= NULL
```
Fixes GCC 5 warnings of the form:
core/io/http_client.cpp:288:9: warning: enumeration value 'STATUS_SSL_HANDSHAKE_ERROR' not handled in switch [-Wswitch]
core/io/marshalls.cpp:806:9: warning: enumeration value 'AABB' not handled in switch [-Wswitch]
Those can be trivial cases where adding a default fallback is the solution,
or more complex issues/hidden bugs where missed values are actually meant
to be handled.
This allows more consistency in the manner we include core headers,
where previously there would be a mix of absolute, relative and
include path-dependent includes.
Using `misc/scripts/fix_headers.py` on all Godot files.
Some missing header guards were added, and the header inclusion order
was fixed in the Bullet module.
editing nodes in the polygon2d editor now updates the polygon in realtime; the previous outline is shown, but this can be disabled via a new editor setting
Currently we rely on some undefined behavior when Object->cast_to() gets
called with a Null pointer. This used to work fine with GCC < 6 but
newer versions of GCC remove all codepaths in which the this pointer is
Null. However, the non-static cast_to() was supposed to be null safe.
This patch makes cast_to() Null safe and removes the now redundant Null
checks where they existed.
It is explained in this article: https://www.viva64.com/en/b/0226/
I can show you the code
Pretty, with proper whitespace
Tell me, coder, now when did
You last write readable code?
I can open your eyes
Make you see your bad indent
Force you to respect the style
The core devs agreed upon
A whole new world
A new fantastic code format
A de facto standard
With some sugar
Enforced with clang-format
A whole new world
A dazzling style we all dreamed of
And when we read it through
It's crystal clear
That now we're in a whole new world of code
