1. Drop dead prepareGeometryChange()/update() calls in
setPotential(), split unrelated terminaleditor.h re-indent into its
own change
2. Removed: setPotential() had prepareGeometryChange()/update() left over from
the label-display mechanism that was dropped before this PR
New QLineEdit (m_potential_le) between Type and Nom: an optional,
symbol-author-chosen grouping identifier shared by terminals that
belong to the same physical terminal within a multi-terminal block.
Stored as TerminalData::m_potential (new field, persisted as the
"potential" XML attribute, empty by default).
Used by relatedPotentialTerminal() in terminal.cpp: when
potential_isolating is enabled on a Terminal-type element, terminals
sharing a non-empty, matching potential value now stay electrically
linked to each other instead of every terminal in the block being
isolated from every other one.
Tooltip on the field for explanation
a) using a system provided KF6
b) downloading and compiling KF6
c) using the vendored-in re-creation of the functionality
The behaviour for both Qt5 and Qt6 is steered with the same two variables which were renamed to become version agnostic:
a) BUILD_WITH_KF=ON BUILD_KF=OFF
b) BUILD_WITH_KF=ON BUILD_KF=ON
c) BUILD_WITH_KF=OFF
The version is automatically derived from the chosen Qt major version.