Optional include for build-dir header to exclude it from core.a when nobuild opts are created / used. Preventive reads before writes, tooPlus, missing change to makecorever.py doing read before writePrefer to use --output-dir in scripts, tests/device *must* beout-of-tree for caching to work properly (avoid changing core nested dirs)Assume 'aggressive caching' is normal mode of operation, no need for special treatment(can be checked by looking at .d files in the build dir)Even CI uses arduino-cli ~/.cache/arduino/{sketch,core} for buildingAllow sketches without globals.h to share core.a, rebuild otherwise(same sketch cache is retained, core.a & .o's reused)Drop manual logging in favour of 'import logging'. Arduino-CLI might still needtweaks in debug mode, though. Output flushing does not always happen promptly.Allow multiple entries for the same name, which are then merged.Allow spaces between @ and the signature words.Allow to use line right after signature.Syntax warnings show relevant snippet from globals.h

bump global build options page in the menu hierarchyshare pydoc blob as rst instead, reference on the main pagenote that aggressive caching opts are only for IDE 1.x

…. funcs