make rods more rare

minor maps

Add inscribable arches for other book types.
Use 'container'/weight_limit to define capacity of inscribables in characters.
Add treasures/arches to specify books with/without text.
Scorn and Navar Public Libraries use these so they don't generate inscribables.
Fix bug allowing theft of blank books from libraries.
Fix bug preventing adding an adjective to a book name if the titles are used up.
Change error message on reading empty book to be more clear.
Change error message on failed inscription [too much text] to be more informative.
Looking at an inscribable will tell you what you can do with it/what its capacity is in a hint.
Fix broken debug statements in book generation.

alchemy spell changes and added new alchemy spell class graphic

- new type: INSCRIBABLE
- inscription only works on inscribable items (spellscrolls special cased)
- add new empty scroll, empty book and empty mailscroll archetypes
- use mailscroll in ipo.

made stat potions more rare another time. made improvement potions also more rare.

changed the random_potion treasurelist to not output
stat potions in 100% of cases on maps with a low difficulty.
stat potions got more rare with this now, map makers should not fear
to put a random potion on their map now without outbalancing the game
so easily. The chance of a stat potion got reduced to 15%.
(i already see it coming that there are too few stat potions out there :-)

remove trailing spaces