added more config options, among others an option to run depclean on

gentoo

sau/gentoo.py

@@ -255,3 +255,25 @@ def pkg_upgrade():
         for line in out.splitlines():
             if line.startswith(' * '):
                 log.warning(line)
+
+    if conf.getboolean('default', 'do_depclean', fallback=False):
+        cmd = [ EMERGE_PATH, '--color', 'n', '-q', '--depclean' ]
+        log.debug('Executing "{}"'.format(' '.join(cmd)))
+        proc = subprocess.Popen(
+                cmd,
+                stdout = subprocess.PIPE,
+                stderr = subprocess.PIPE)
+        out, err = proc.communicate()
+        out = out.decode('utf-8')
+        err = err.decode('utf-8')
+        if proc.returncode != 0 or err:
+            log.error('depclean returned {}'.format(proc.returncode))
+            for line in out.splitlines():
+                log.error('stdout: {}'.format(line))
+            for line in err.splitlines():
+                log.error('stderr: {}'.format(line))
+        else:
+            log.info('depclean complete')
+            for line in out.splitlines():
+                if line.startswith(' * '):
+                    log.warning(line)