7/19 Update: Stat and Battle Changes

Made some changes to stat growth (agility in particular), and increased frequency of "grouped" enemies (more than 1 of same type).  Also a few bug fixes, and some modifications of random battle frequency.

*  Fixed a couple of shop bugs regarding the leather shield (including the 0 cost in Rainbow Town),  and put in the new leather shield graphic.

*  Added a 33% chance of getting the same enemy more than once, in addition to the normal chance of that enemy.

*  Made a few tweaks to random battle frequency in all 4 chapters.

*  Agility now increases same rate as Attack/Defense/Magic Defense/Wisdom.

*  Initiative is now based on square root of Agility, which enabled me to reduce the constant used, and this balances initiative MUCH better than previously.  This will mainly have the effect of having characters/enemies attacking at a more similar rate than before.

*  Fixed a bug in Chapter 3 regarding how often a 2nd enemy appears in first zone.

*  Other stats had their increase per level adjusted a little,  and a few mistakes were also corrected.

*  A few other minor fixes and changes.