Fixes the following GCC 5 warnings:
```
core/os/file_access.cpp:49:19: warning: the address of 'FileAccess::create_func' will always evaluate as 'true' [-Waddress]
servers/audio_server.cpp:192:70: warning: comparison with string literal results in unspecified behaviour [-Waddress]
drivers/gles2/rasterizer_storage_gles2.cpp:4095:90: warning: NULL used in arithmetic [-Wpointer-arith]
modules/gdnative/register_types.cpp:237:3: warning: deprecated conversion from string constant to 'char*' [-Wwrite-strings]
platform/android/export/export.cpp:207:1: warning: deprecated conversion from string constant to 'char*' [-Wwrite-strings]
modules/gdscript/gdscript.h:150:67: warning: returning reference to temporary [-Wreturn-local-addr]
servers/physics_2d/collision_object_2d_sw.h:119:56: warning: returning reference to temporary [-Wreturn-local-addr]
servers/physics_2d/collision_object_2d_sw.h:123:56: warning: returning reference to temporary [-Wreturn-local-addr]
servers/physics_2d/collision_object_2d_sw.h:127:50: warning: returning reference to temporary [-Wreturn-local-addr]
servers/physics_2d/collision_object_2d_sw.h:131:52: warning: returning reference to temporary [-Wreturn-local-addr]
editor/plugins/skeleton_editor_plugin.cpp:34:36: warning: extra tokens at end of #include directive
modules/bullet/bullet_types_converter.cpp:31:9: warning: #pragma once in main file
editor/import/editor_scene_importer_gltf.cpp:1996:51: warning: name lookup of 'i' changed
modules/visual_script/visual_script_property_selector.cpp:402:45: warning: name lookup of 'E' changed
scene/gui/tree.cpp:1268:25: warning: name lookup of 'i' changed
scene/resources/visual_shader.cpp:808:32: warning: name lookup of 'i' changed
```
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.
Implements an Audio bus effect that outputs the audio from the bus into a wav file
Now channels audio recording into an AudioStreamSample instead of saving to wav
This commit makes operator[] on Vector const and adds a write proxy to it. From
now on writes to Vectors need to happen through the .write proxy. So for
instance:
Vector<int> vec;
vec.push_back(10);
std::cout << vec[0] << std::endl;
vec.write[0] = 20;
Failing to use the .write proxy will cause a compilation error.
In addition COWable datatypes can now embed a CowData pointer to their data.
This means that String, CharString, and VMap no longer use or derive from
Vector.
_ALWAYS_INLINE_ and _FORCE_INLINE_ are now equivalent for debug and non-debug
builds. This is a lot faster for Vector in the editor and while running tests.
The reason why this difference used to exist is because force-inlined methods
used to give a bad debugging experience. After extensive testing with modern
compilers this is no longer the case.
Fixes NaN roughness in Godot when hardness in Blender is set to more than 255.
Also corrects dependency: more hardness = more roughness (it says shininess, but it actually is hardness).
