Amulet of magical breathing increases energy regen

Normally energy regen is 1d2 or 1d3, so wearing the amulet increases
that to 1d4 or 1d5.  The only way to get energy regeneration is via
The Eye of the Aethiopica, so you cannot have both at the same time.

doc/fixes3-7-0.txt

@@ -1585,6 +1585,7 @@ give experience if opening Schroedinger's Box causes death of the cat inside
 priest donation amounts are explicitly stated, randomized slightly, based on
        peak rather than current level, and allow for bulk donations (buying
        larger amounts of clairvoyance/protection) if you have a lot of gold
+amulet of magical breathing increases power regeneration
 
 
 Fixes to 3.7.0-x General Problems Exposed Via git Repository

src/allmain.c

@@ -607,6 +607,9 @@ regen_pw(int wtcap)
                               / 6)))) || Energy_regeneration)) {
         int upper = (int) (ACURR(A_WIS) + ACURR(A_INT)) / 15 + 1;
 
+        if (EMagical_breathing)
+            upper += 2;
+
         u.uen += rn1(upper, 1);
         if (u.uen > u.uenmax)
             u.uen = u.uenmax;