Patch for SYSBOOKS package

[OldnGrey]

Added:
GM Command to toggle book between read/write and readonly

Deleted:
Removed unused bookstorage.cfg file

Edited:
* itemdesc.cfg - added commented out example of a shard common book defined in itemdesc
* methods.src - fixed reading of book contents from itemdesc.cfg entry.

NOTES:
* Books defined in itemdesc cannot be editied
* When editing books using cprops (for Author, Title, and Contents), the changes are saved in datafiles, not back to the cprop
* When opening a book the scripts search for entries in datafile, cprops then itemdesc entries in that order. They will only write back to datafiles.