Add a qmk clone command

.gitignore

@@ -102,3 +102,6 @@ venv.bak/
 
 # mypy
 .mypy_cache/
+
+# QMK
+qmk_firmware

qmk_cli/clone.py

@@ -0,0 +1,40 @@
+"""Clone a qmk_firmware fork.
+"""
+import os
+import subprocess
+from pathlib import Path
+
+from qmk_cli.milc import cli
+
+default_repo = 'qmk_firmware'
+default_fork = 'qmk/' + default_repo
+default_branch = 'master'
+
+@cli.argument('--baseurl', default='https://github.com', help='The URL all git operations start from.')
+@cli.argument('-b', '--branch', default=default_branch, help='The branch to clone.')
+@cli.argument('destination', default=os.environ['QMK_HOME'], nargs='?', help='The directory to clone to.')
+@cli.argument('fork', default=default_fork, nargs='?', help='The qmk_firmware fork to clone')
+@cli.entrypoint('Clone a qmk_firmware fork.')
+def main(cli):
+    qmk_firmware = Path(cli.args.destination)
+    git_clone = [
+        'git',
+        'clone',
+        '--recurse-submodules',
+        '--branch=' + cli.config.general.branch,
+        '/'.join((cli.config.general.baseurl, cli.args.fork)),
+        cli.args.destination,
+    ]
+
+    if qmk_firmware.exists():
+        cli.log.error('Destination already exists: %s', cli.args.destination)
+        exit(1)
+
+    with subprocess.Popen(git_clone, stdout=subprocess.PIPE, bufsize=1, universal_newlines=True) as p:
+        for line in p.stdout:
+            print(line, end='')
+
+    if p.returncode != 0:
+        cli.log.error('git clone exited %d', p.returncode)
+    else:
+        cli.log.info('Successfully cloned %s to %s!', cli.args.fork, cli.args.destination)