fix old tn format in spells

spells/Fire2.tex

@@ -29,5 +29,5 @@
   {\spellArea\ fires go out}% Description
   {
     \spellArea\ fires extinguish, becoming nothing but a wiff of smoke.
-    Candles are \tn{6}, torches \tn{7}, hearths \tn{8}, and bonfires demand \tn{9} or more.
+    Candles are \tn[6], torches \tn[7], hearths \tn[8], and bonfires demand \tn[9] or more.
   }

spells/Light2.tex

@@ -7,7 +7,7 @@
   {
     The caster grows any source of light into a painful glare, covering a massive area.%
     \footnote{$7!$ squares, but who's counting?}
-    When this light springs up suddenly in the dark, anyone looking towards it makes a Wits + Vigilance test (\tn{9}) or loses \arabic{spelllevel}~\gls{ap}.
+    When this light springs up suddenly in the dark, anyone looking towards it makes a Wits + Vigilance test (\tn[9]) or loses \arabic{spelllevel}~\gls{ap}.
   }
 
 \spell{Were Light}% Name
@@ -18,7 +18,7 @@
   {any spark blooms into a warm light}% Description
   {
     This light attaches to a target, hovering around them like sparkling oil-stain.
-    The light springs up suddenly, and targets used to the dark, make a Wits + Vigilance test (\tn{9}) or loses \arabic{spelllevel}~\gls{ap}.
+    The light springs up suddenly, and targets used to the dark, make a Wits + Vigilance test (\tn[9]) or loses \arabic{spelllevel}~\gls{ap}.
 
     The light fades if left in the darkness for a full \gls{interval}, or if batted and prodded for a couple of rounds.
   }
@@ -36,6 +36,6 @@
 
     \setcounter{track}{\value{spelllevel}}
     \addtocounter{track}{7}
-    Onlookers in twilight must roll Wits + Vigilance, \tn{\arabic{track}}, to see through the illusion, and more darkness can increase the \gls{tn}.
+    Onlookers in twilight must roll Wits + Vigilance, \tn[\arabic{track}], to see through the illusion, and more darkness can increase the \gls{tn}.
   }
 

spells/Mind1.tex

@@ -8,7 +8,7 @@
     The target finds sudden joy and fascination with their current task.
     The task always takes the form of a single verb -- `blacksmithing', `walking', `singing' -- never something convoluted like `the mission to kidnap the warden', or `finding the right paints for the colour of a Sunrise'.
 
-    \Glspl{npc} targeted by the spell can make a Wits + Academics roll, \tn{8}, to break away from the task.
+    \Glspl{npc} targeted by the spell can make a Wits + Academics roll, \tn[8], to break away from the task.
     \Glspl{pc} afflicted by the spell cannot gain any further \glspl{xp} for the a full day (four \glspl{interval}), unless they complete the current \gls{interval} without wavering from their task.
 
   Anyone sleeping almost certainly remains asleep, and rolls to wake up suffer a -4 penalty.