fix Issue 3449 - const and invariant struct members do not behave according to spec
add target for default dmd.conf

- works for the common dmd/druntime/phobos folder layout

- does not overwrite existing dmd.conf files
Explicitly cast AA value to void*
Merge pull request #4121 from yebblies/aavoid

[DDMD] Explicitly cast AA value to void*
use std.algorithm: cmp
better error message when the same file is specified twice on the command line
Merge pull request #4122 from 9il/cmp

use std.algorithm: cmp
Merge pull request #4098 from MartinNowak/dmdConf

add target for default dmd.conf
Merge pull request #4123 from rainers/issue13704

Fix issue 13704 - Confusing error message when passing the same on the command line twice
Merge pull request #4042 from 9rnsr/fix3449

Issue 3449 - const and invariant struct members do not behave according to spec
Fix Issue 13707 - msvc32 C++ struct return ABI not followed for structs with constructors

A constructor should stop a struct from being passed in registers on win32/C++.
Change traits table back to using a sentinel value
Add manually ported frontend source files to version control
Add settings file and makefile targets to build ddmd
Add generated source to .gitignore
Add magicport source to repo
memory hacks
Hack-hacky hack hack
HOST_DC