modularize src

+ merge main.py and manage.py
+ move start logic to swingmusic/__main__.py
+ add a run.py on the project root

swingmusic/lib/pydub/appveyor.yml

@@ -0,0 +1,30 @@
+build: false
+environment:
+  matrix:
+    - PYTHON: "C:/Python27"
+      FFMPEG: "4.2.3"
+    - PYTHON: "C:/Python34"
+      FFMPEG: "4.2.3"
+    - PYTHON: "C:/Python35"
+      FFMPEG: "4.2.3"
+    - PYTHON: "C:/Python36"
+      FFMPEG: "4.2.3"
+    - PYTHON: "C:/Python36"
+      FFMPEG: "latest"
+matrix:
+  allow_failures:
+    - FFMPEG: "latest"
+init:
+  - "ECHO %PYTHON%"
+  - ps: "ls C:/Python*"
+install:
+  - "%PYTHON%/python.exe -m pip install wheel"
+  - "%PYTHON%/python.exe -m pip install -e ."
+  # Install ffmpeg
+  - ps: Start-FileDownload ('https://github.com/advancedfx/ffmpeg.zeranoe.com-builds-mirror/releases/download/20200915/ffmpeg-' + $env:FFMPEG + '-win64-shared.zip') ffmpeg-shared.zip
+  - 7z x ffmpeg-shared.zip > NULL
+  - "SET PATH=%cd%\\ffmpeg-%FFMPEG%-win64-shared\\bin;%PATH%"
+  # check ffmpeg installation (also shows version)
+  - "ffmpeg.exe -version"
+test_script:
+  - "%PYTHON%/python.exe test/test.py"