Add Log.h (in IfcViewerCore) — a tiny stream-style logger that backs
fprintf(stderr,...), with overloads for the common primitives + char
strings. Mimics qInfo()/qWarning()'s syntax surface enough that
mass-replacing qInfo()→Log::info() and qWarning()→Log::warn() keeps
existing call sites parsing unchanged; .noquote() / .nospace() exist
as compat no-ops so chained qInfo().noquote()<<x<<y patterns survive.
QString streaming is a transitional concern — the QString → std::string
sweep (#80) hasn't landed yet, so ViewportWindow and friends still
construct QStrings for log payloads. LogQt.h (in IfcViewer, not Core)
adds the QString / QStringView operator<< overloads so those streaming
sites work without source changes during the in-flight Qt removal.
When #80 retires QString, LogQt.h drops out.
ViewportWindow.cpp: 132 qInfo/qWarning callsites converted. The two
printf-style qInfo("fmt %s", ...) callsites get fprintf with explicit
[info]/[warn] prefixes to keep the output discoverable.
Also de-Qt'd:
AreaMeasurement.cpp — 1 qInfo("fmt", …) → fprintf
SceneLoader.cpp — 4 qDebug + 1 qWarning printf-style → fprintf
GeometryStreamer.cpp — 2 qDebug printf-style → fprintf
ifcviewer-minimal/main.cpp — 2 qWarning << → Log::warn
Drops <QDebug> from each. Closes#82.
Builds: desktop / bonsai / web all green. Tests 100/100 pass.
Dion Moult