small refactor: reuse code, increase readability

[nobkd]

bin/opi

• update search regex: (L24)
  • \d for 0-9
  • * instead of {0,}

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opi/__init__.py

• saving the results of get_cpu_arch() in a variable to reuse them (L307-320)
• simplify if statement for setting the weight of a result (L348)
• deduplicate URL building for GPG key in install_binary() (L394)
• use default math function log10() instead of log() with parameter 10 (L443)
• default_answer for ask_yes_or_no() is now 'y' (L423, plugins) ⇾ if not liked, I can undo the last commit

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opi/plugins/__init__.py

• removing (object) inheritance as not needed in python3
• use str.endswith() instead of string comparison by range (L23)

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opi/config/__init__.py

• remove unused code

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opi/plugins/yandex-browser.py

• get last part of split string with [-1] instead of [2]

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• some minimal changes