[FIX] Webmail Contacts: pagination of contacts

Pagination of contacts would show Page: 1/1 even when it was obvious that there were more than one pages when many contacts have been added. And the maximum number of contacts to display on a page was hardcoded to 20.

I made the pagination to display as expected no matter how many number of contacts exist. Then I made value for maximum number of contacts per page to use value of maxRecords from $prefs. If $prefs['maxRecords'] is not set, then 20 is used.

I also made changes that make all numbered page links to be clickable links except the currently opened page number.

Additionally, if an initial alphabet for contacts to display is set, this is now retained when performing view, edit or remove actions on a contact.

@marclaporte @jonnybradley @luciash