Ci updates & closer to windows builds

* chore: update some ci

* feat: no more libiconv

* refactor: updates for updated mmime api

* fixup: correct mmime path

* cleanup

* use newer visual studio

* Update appveyor.yml

* unify libc imports and improve windows situation

* refactor: use rust based sleep

* improve cross platform state of types

* docs: update readme badges

appveyor.yml

@@ -0,0 +1,37 @@
+environment:
+  matrix:
+    # MinGW
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      TARGET: i686-pc-windows-gnu
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      TARGET: x86_64-pc-windows-gnu
+
+    # MSVC
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      TARGET: i686-pc-windows-msvc
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      TARGET: x86_64-pc-windows-msvc
+
+install:
+  - ps: >-
+      If ($Env:TARGET -eq 'x86_64-pc-windows-gnu') {
+        $Env:PATH += ';C:\msys64\mingw64\bin'
+      } ElseIf ($Env:TARGET -eq 'i686-pc-windows-gnu') {
+        $Env:PATH += ';C:\msys64\mingw32\bin'
+      }
+  - appveyor DownloadFile https://win.rustup.rs/ -FileName rustup-init.exe
+  - rustup-init -yv --default-host %target% --default-toolchain none
+  - set PATH=%PATH%;%USERPROFILE%\.cargo\bin
+  - rustc -vV
+  - cargo -vV
+  - cd %APPVEYOR_BUILD_FOLDER%
+  - git submodule update --init --recursive
+
+build: false
+
+test_script:
+- cargo test
+
+cache:
+  - target
+  - C:\Users\appveyor\.cargo\registry