All usages actually want to ensure the directory is present,
and don't care about having a separation between existence check
and creation.

It doesn't make sense to have those in two separate modules.

This removes the range API and instead uses Appender,
while using a limited and centralized set of functions
to read/write from files.
The end goal is to permit dependency injection,
which is a pre-requisite to extending the test-suite.

We don't actually use URL here, nor should we,
we use path, so correct the import.

The new module replaces dub.internal.vibecompat.core.log by using the
same function names, but implementing colored output and the left
fixed-width tag. Overloaded functions are provided to output colored
text.

Still missing initLogging() and non-TTY stdout/stderr detection

Matches the changes done in vibe.d 0.8.x and vibe-core.

Since `std.file.copy` provides a means to preserve attributes of a file
as of DMD 2.067.0 or later, it is preferable to use this option rather
than having a custom-written solution.  `version (Posix)` special-casing
is therefore used only where the DMD version does not support it.

Note that where the `version (Posix)` code uses a `chown` call followed
by a `chmod` call, `std.file.copy` only uses a `chmod`.  This is not
expected to cause any issues but should be borne in mind as a possible
breaking change for some use-cases.

Fixes https://github.com/dlang/dub/issues/992.

Since opening non-ASCII filenames on Windows is fixed for the latest DMD version, it now only has to be made sure to use a recent compiler to build DUB.

Also some minor code style fixes.

hardlink files into target dir

- fixes Issue #457 - stale symlinks

- also thisExePath will now point to the target binary

- also implemented on Windows

- fallback to copy

Also contains two minor additional style fixes.

Conflicts:
	source/dub/dub.d
	source/dub/generators/build.d
	source/dub/generators/generator.d
	source/dub/package_.d