Several Improvements to Emacs and NixOX

Emacs:
Fix: Emacs mouse wheel scrolling was overshooting sometimes
Feat: Hide more useless messages in the echo are (NO CHILDREN)
Feat: Add presentation mode using org-present
Fix: Fix org-tempo angled brackets insertion
Feat: better math mode in AucTeX in lieu of some yasnippet bits
Fix: add treesitter modes to eglot for automatic startup
Fix: Make mu4e automatic sender address choosing more robust

NixOS:
Feat: Add oama derivation
Feat: Add main email sender address to config
Feat: Add opacity toggle (for use with presentation mode)

scripts/toggle_opacity.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+swaymsg opacity plus 0.01
+
+if [ $? -eq 0 ]; then
+        # opacity was not 1, we toggle off
+        swaymsg opacity 1
+else
+        # opacity was 1, we toggle on
+        swaymsg opacity 0.95
+fi