Combat bard songs

[altsan]

First, thanks for the great work on this.

I've been comparing against BT3 on C64, and BT1 and BT2 for DOS, and in all those games Bard songs last through the entire battle and are 'stackable'.

(I know the manual claims they should expire after one round, but on reflection that makes no sense -- in many cases, especially in the later game, the bard's combat action is going to come after most of the monsters and fighting characters have attacked, so any song played will frequently be useless in that round. The way the game is actually written in BT1, BT2, and BT3 for C64, makes much more sense.)

I wrote a smallish patch to address this. I've been playing with it in place for a couple of months now, and it seems reliable.

This patch causes combat Bard songs to last until the end of battle. Sanctuary Score, Bringaround Ballad, and Rhyme of Duotime will also 'stack', both with themselves and with each other. This duplicates the behaviour of the C64 version, and is in line with BT1 and BT2 behaviour as well. I've also tested with having multiple Bards in a party playing different songs at the same time - this also works.

The attached zip contains two versions of the patch, as diffs.

• bt3-dos-patch_ALT_2017-11-04.diff was taken against commit e045b0b (Nov.12 2014) which is the state of the code when I started working on this. This is what I've been testing with, and it works well.
• bt3-dos-patch_ALT_2018-01-29.diff was taken against commit bce4e94 (Jan.29 2018). I did a quick adaptation of my changes to the latest codebase - however, I have not tested this as I have some build issues with the current snapshot (missing 'foreachq4.m4'?). The changes are pretty simple and fairly self-contained, so I hope this still works properly. (They were applied to the separated asm files; the diff picked the changes to the combined thief.asm as well but I assume you can ignore that.)

bt3-dos-patch_ALT_combat_songs.zip