toolbar block icons centred in their 16px box (test for all icons), tutorials say where the objects tab is

CHANGELOG.md

@@ -4,6 +4,9 @@
 
 - **Editor:** flying with the right mouse button + W A S D / Q E now works even when another part of
   the window (a text field, a dock) still had the keyboard focus.
+- **Editor:** the block, pillar and invisible-box icons sat too low in the toolbars (drawn outside
+  their box); a test now keeps every icon inside its 16 × 16 box.
+- **Tutorials** say where the Objects panel is (the ⊙ tab next to *Outliner*).
 
 ## 0.2.2 – 2026-11-07