Remove OS.get_system_time_secs/get_system_time_msecs and change OS.get_unix_time return type to double

Fix building mono release templates

Add dinput nullptr checks.

Activate emscripten with no-embedded option.

Do not probe joypads if DirectInput cannot be initialized.

Fix ProjectSettings.save_custom documentation

Correct Bullet's default Area angular damp value.

Split `Geometry` singleton into `Geometry2D` and `Geometry3D`

SCons: Allow to read `custom_modules` option via a file

The `custom_modules` option was only read via the command line
by fetching `ARGUMENTS` dictionary directly.

Instead, the option's value can now be read via any existing
configuration files (`custom.py`) as well as command line, while also
updating the environment.

GitHub: Remove feature request placeholder template

We now have a proper link to godotengine/godot-proposals thanks to
#39019 and #39132, so that hacky 'Don't open issues here' template
is no longer needed.

SCons: Prefer `Exit()` method over `sys.exit()`

Fix GitHub issue template config not working

Travis CI: Use the Xcode 11.5 image for macOS builds

It was in the wrong folder

Sconscript provides it's own `Exit()` method which is currently
an alias for `sys.exit()` internally, with the only difference that if
no exit code is specified, it defaults to 0.

This encourages the usage of SCons-implemented methods like
`Glob()` over `glob.glob()`, which may overcome limitations of the
built-in Python features in the future.

SCons: use `OrderedDict` to ensure insertion order of modules

The insertion order for dictionaries is only a language feature for
Python 3.6/3.7+ implementations, and not prior to that.

This ensures that the engine won't be rebuilt if the order of detected
modules changes in any way, as the `OrderedDict` should guarantee
inerstion order.

Add missing consumePurchase plugin method for GodotPayment

Remove "erasing" print from Directory.remove (Windows)

Use translated docs in PropertySelector

Fixes #39106

And do the dedent and stripping for both translated and
non-translated strings for consistency, and so that we
don't need to do it at the call site.

Tweak the DirectInput initialization failure message

This closes #36662.

Validate that `Use Custom Build` is enabled when `Plugins` are selected

makerst: Print status messages to make the CI output clearer

This also removes an unused method.

Remove `GodotPayment` from the default build template

Fix unsigned integer bug in LocalVector::erase

`erase()` calls `find()` to get the index of the element to remove, if
any.

https://github.com/godotengine/godot/blob/c2151e18135817c9f926a5a00341016ac77301d4/core/local_vector.h#L77-L81

`find()` returns a signed integer. In particular, it returns -1 if
no element is found. Since `erase()` converts this to an unsigned type, the
wrong element may be erroneously removed from the vector.

Other ways to fix this would involve changing function signatures, so
this seemed to be the least disruptive change.

Fixes #38884

SCons: Move build progress related logic out of main SConstruct