WIP: fix separator logic to be in line with i3status

[ultrabug]

closes #2116

[lasers]

Months ago, I made a small diff that makes py3status to be in more line with i3status too (just for the terminal)... made after #2104.

commit d2ef7e4f3b35df093bb7b6c41b53d516e88a9a23
Author: lasers <lasers@lasers.com>
Date:   Tue Apr 5 03:41:33 2022 -0500

    core: autodetect output_format

diff --git a/py3status/constants.py b/py3status/constants.py
index 2868625e..a0375ccd 100644
--- a/py3status/constants.py
+++ b/py3status/constants.py
@@ -7,7 +7,7 @@ GENERAL_DEFAULTS = {
     "color_separator": "#333333",
     "colors": True,
     "interval": 5,
-    "output_format": "i3bar",
+    "output_format": None,
 }
 
 MAX_NESTING_LEVELS = 4
diff --git a/py3status/core.py b/py3status/core.py
index 9adab8bf..98b9f022 100644
--- a/py3status/core.py
+++ b/py3status/core.py
@@ -568,6 +568,16 @@ class Py3statusWrapper:
         self.log("config file: {}".format(self.config["i3status_config_path"]))
         self.config["py3_config"] = process_config(config_path, self)
 
+        # autodetect output_format
+        output_format = self.config["py3_config"]["general"]["output_format"]
+        if output_format is None:
+            if sys.stdout.isatty():
+                print("py3status: trying to auto-detect output_format setting")
+                print('py3status: auto-detected "term"')
+                output_format = "term"
+
+        self.config["py3_config"]["general"]["output_format"] = output_format or "i3bar"
+
         # read resources
         if "resources" in str(self.config["py3_config"].values()):
             from subprocess import check_output

... then the next / this PR could be looked at to fix separator hack / issue... It would be ideal to support both (py3status) boolean + (i3status) string options... Maybe by converting False to "" and ignoring True. I haven't made anything for this hack / issue.

[lasers]

(Self note) Don't test i3status in terminal because i3status wasn't designed for that and doesn't honor separator = false config in the terminal, but will work fine on i3bar.

[ultrabug]

Either we rework it properly, or leave it as is