Alphabetical navigation

*Title: Alphabetical navigation.

*Documentation:

Objects can be filtered by first letter.
If content.ini[AlphabeticalFilterSettings].ContentFilterList[] is not empty
alphabetical navigator will be enabled.
Alphabetical navigation is used with google navigation in the children window of content/view,
in content/browse and trash.

The navigator uses any alphabets (see content.ini[AlphabeticalFilterSettings].AlphabetList[]).

(Make sure that your alphabets in content.ini[AlphabeticalFilterSettings].ContentFilterList[]
is supported by i18n.ini[CharsetSettings].Charset. All unsupported letters will be shown like question mark '?')

* New settings:

New INI settings in content.ini[AlphabeticalFilterSettings] have been added:

- ContentFilterList[]
  List of alphabets that will be used in alphabetical navigation.
  Alphabets will be fetched from AlphabetList[<name of alphabet>]
  For example:
      ContentFilterList[]=<name of alphabet>
      ContentFilterList[]=eng-GB
      ContentFilterList[]=ger-DE
  If array is empty means the alphabetical navigation will be disabled.

- AlphabetList[]
  Alphabet range in unicode (range of english alphabet is between 97 and 122).
  You can use range (e.g. 97-122) and/or sequence of letters (e.g. 248,249).
  For example:
      AlphabetList[eng-GB]=97-122
      AlphabetList[ger-DE]=97,228,98-111,246,112-115,223,116,117,252,118-122
      AlphabetList[rus-RU]=1072-1103
      AlphabetList[nor-NO]=97-122,230,248,229

- EnableUnusedLetters=true/false
  If true unused letters in alphabetical navigation (when browsing or fetching subitems)
  will be disabled.
  For example:
      if there are no objects with 'a' first letter in the object name 'a' letter will be disabled in alphabetical navigation.

*Implementation details:

1) Added supporting of 'ObjectNameFilter' parameter to
eZContentObjectTreeNode:subTree() and eZContentObjectTreeNode:subTreeCount()

2) Added 'objectname_filter' parameter to next fetch functions:

- list
- list_count
- tree
- tree_count
- trash_count
- trash_object_list

Usage:
      {let children_count=fetch( content, list_count, hash( parent_node_id, $node.node_id,
                                                            objectname_filter, $view_parameters.namefilter ) )
           children=fetch( content, list, hash( parent_node_id, $node.node_id,
                                                sort_by, $node.sort_array,
                                                limit, $number_of_items,
                                                offset, $view_parameters.offset,
                                                objectname_filter, $view_parameters.namefilter ) ) }

Now you can use object name filtering by first letter like this:

      http://host/<site_access>/content/view/full/2/(namefilter)/a

3) Also alphabet() tpl function has been added.
Returns alphabets for alphabetical navigation.
The function has no params.

Usage:
      {alphabet()}

=============

If you want to use alphabetical navigator
you should
1. Add "hash( ... objectname_filter, $view_parameters.namefilter )" to fetch operations in tpls.
   (see 'Implementation details'[2])
2. Change
      uri='design:navigator/google.tpl'
   to
      uri='design:navigator/alphabetical.tpl'
   in 'include' operation.

   For example:
     {include name=navigator
              uri='design:navigator/alphabetical.tpl'
              page_uri=$node.url_alias
              item_count=$children_count
              view_parameters=$view_parameters
              node_id=$node.node_id
              item_limit=$number_of_items}