capture QR codes from camera and major refactoring

- add GUI for QR code capturing from camera (CV2 is used)
- support different QR readers: ZBAR,QREADER,QREADER_DEEP,CV2,CV2_WECHAT
- support several input files
- add option to ignore duplicate otps
- write warnings and errors to stderr
- add output coloring
- rename project from extract_otp_secret_keys to extract_otp_secrets
- improve help
- clean verbose level output
- use Python type hints and check with mypy
- use f-strings
- clean up code
- add more tests
- calculate code coverage
- use src-layout: move files and folders
- support wheel packing
- enhance README.md
- bugfixes
    * fix -k -
    * fix utf-8 encoding on windows

.vscode/launch.json

@@ -0,0 +1,39 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "Python: extract_otp_secrets.py",
+            "type": "python",
+            "request": "launch",
+            "program": "src/extract_otp_secrets.py",
+            "args": [
+                "example_export.txt"
+            ],
+            "console": "integratedTerminal"
+        },
+        {
+            "name": "Python: extract_otp_secrets.py stdin pic",
+            "type": "python",
+            "request": "launch",
+            "program": "src/extract_otp_secrets.py",
+            "args": [
+                "-",
+                "<",
+                "test/test_googleauth_export.png",
+            ],
+            "console": "integratedTerminal"
+        },
+        {
+            "name": "Python: extract_otp_secrets.py capture",
+            "type": "python",
+            "request": "launch",
+            "program": "src/extract_otp_secrets.py",
+            "args": [
+            ],
+            "console": "integratedTerminal"
+        },
+    ]
+}