Lots of changes here:

Lots of changes here:
- Added $clobber as argument to InsertPage. If $clobber, then use 'replace '; otherwise use 'insert'i. Pages going into the current store should clobber, but pages going into the archive should not. (Assuming that an unlimited number of pages are kept. I still need to implement archive limiting...)
- Created function ReplaceCurrentPage.
- Moved link updating from InsertPage to ReplaceCurrentPage.
- Renamed SaveCopyToArchive to SavePageToArchive.
- Created function RetrievePageVersions. Returns an arary of page hashes that contains all versions of the specified page.
- Added $version as argument to RetrievePage. It needs to know which version to get. Version 0 (zero)is magic, and always refers to the current version.
- Created function GetMaxVersionNumber. This is used mostly to determine which version to get for the diffs against current pages.
- Created function IsVersionInWiki.
- Created function IsVersionInArchive.
- Created function SelectStore. Given a page name and a version, this function returns the store where that page resides.

git-svn-id: svn://svn.code.sf.net/p/phpwiki/code/trunk@509 96ab9672-09ca-45d6-a79d-3d69d39ca109