Windows - 'My Music' folder won't be assumed to be on C drive (#387)

* Windows - 'My Music' folder won't be assumed to be on C drive

Windows has a nice registry check to get the absolute path of the 'My Music' folder. This helps because some people change their location of their music folder.

* Updated according to suggestions

Let me know if there are anymore improvements 👍

* Fixups

spotdl/internals.py

@@ -4,6 +4,10 @@ from logzero import logger as log
 
 from spotdl import const
 
+try:
+    import winreg
+except ImportError:
+    pass
 
 try:
     from slugify import SLUG_OK, slugify
@@ -174,8 +178,7 @@ def get_unique_tracks(text_file):
 
     return lines
 
-
-# a hacky way to user's localized music directory
+# a hacky way to get user's localized music directory
 # (thanks @linusg, issue #203)
 def get_music_dir():
     home = os.path.expanduser('~')
@@ -191,6 +194,15 @@ def get_music_dir():
                         if line.startswith('XDG_MUSIC_DIR'):
                             return os.path.expandvars(line.strip().split('=')[1].strip('"'))
 
+    # Windows / Cygwin
+    # Queries registry for 'My Music' folder path (as this can be changed)
+    if 'win' in sys.platform:
+        try:
+            key = winreg.OpenKey(winreg.HKEY_CURRENT_USER, r"Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders", 0, winreg.KEY_ALL_ACCESS)
+            return winreg.QueryValueEx(key, "My Music")[0]
+        except (FileNotFoundError, NameError):
+            pass
+    
     # On both Windows and macOS, the localized folder names you see in
     # Explorer and Finder are actually in English on the file system.
     # So, defaulting to C:\Users\<user>\Music or /Users/<user>/Music