Note: this breaks the plugin API for document functions,
document signal callbacks, msgwin_msg_add() and navqueue_goto_line().
Make all DocumentFuncs use a GeanyDocument* instead of an integer
index, so there's no need to access the documents array or use
DOC_IDX_VALID() - usually just check for non-NULL.
Pass a document pointer to the callbacks of all document-* signals.
Add GeanyDocument::index field for use with the documents array.
Remove DocumentFuncs::get_cur_idx() - use get_current() instead.
Replace DocumentFuncs::get_n_idx() with get_from_page().
Rename DocumentFuncs::find_by_realpath() to find_by_real_path().
Replace DocumentFuncs::remove() with remove_page().
Add 'changed' argument for DocumentFuncs::set_text_changed().
Make NavQueueFuncs and MsgWinFuncs use a GeanyDocument* instead of an
integer index.
Add DOC_VALID() macro.
Add deprecated DOC_IDX() macro to get the document index from a
possibly NULL pointer; deprecate macro DOC_IDX_VALID. These macros
can make porting outside plugins easier; of course, it is better to
rewrite the code to use document pointers.
Use document pointer instead of an index to the documents array
everywhere in the core code.
Rename utils_check_disk_status() in document_check_disk_status() and
move it into document.c.
Adjust plugins to work with these changes.
Add dox for document_set_filetype().
Rename debugging function doc() doc_at() to avoid conflicts.
Update plugin signals dox.


git-svn-id: https://geany.svn.sourceforge.net/svnroot/geany/trunk@2705 ea778897-0a13-0410-b9d1-a72fbfd435f5