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

tests/data/print_verbose_output-v.txt

@@ -0,0 +1,51 @@
+QReader installed: True
+CV2 version: 4.7.0
+QR reading mode: ZBAR
+
+Input files: ['example_export.txt']
+
+1. Secret
+Name:    pi@raspberrypi
+Secret:  7KSQL2JTUDIS5EF65KLMRQIIGY
+Issuer:  raspberrypi
+Type:    totp
+otpauth://totp/pi%40raspberrypi?secret=7KSQL2JTUDIS5EF65KLMRQIIGY&issuer=raspberrypi
+
+
+2. Secret
+Name:    pi@raspberrypi
+Secret:  7KSQL2JTUDIS5EF65KLMRQIIGY
+Type:    totp
+otpauth://totp/pi%40raspberrypi?secret=7KSQL2JTUDIS5EF65KLMRQIIGY
+
+
+3. Secret
+Name:    pi@raspberrypi
+Secret:  7KSQL2JTUDIS5EF65KLMRQIIGY
+Type:    totp
+otpauth://totp/pi%40raspberrypi?secret=7KSQL2JTUDIS5EF65KLMRQIIGY
+
+
+4. Secret
+Name:    pi@raspberrypi
+Secret:  7KSQL2JTUDIS5EF65KLMRQIIGY
+Issuer:  raspberrypi
+Type:    totp
+otpauth://totp/pi%40raspberrypi?secret=7KSQL2JTUDIS5EF65KLMRQIIGY&issuer=raspberrypi
+
+
+5. Secret
+Name:    hotp demo
+Secret:  7KSQL2JTUDIS5EF65KLMRQIIGY
+Type:    hotp
+Counter: 4
+otpauth://hotp/hotp%20demo?secret=7KSQL2JTUDIS5EF65KLMRQIIGY&counter=4
+
+
+6. Secret
+Name:    encoding: ¿äÄéÉ? (demo)
+Secret:  7KSQL2JTUDIS5EF65KLMRQIIGY
+Type:    totp
+otpauth://totp/encoding%3A%20%C2%BF%C3%A4%C3%84%C3%A9%C3%89%3F%20%28demo%29?secret=7KSQL2JTUDIS5EF65KLMRQIIGY
+
+Extracted 6 otps from 5 otp urls by reading 1 infile