[IMPROVED] Better handling of archived shares

Please check the appropriate ticket #1021 for details of the changes
made. Tested locally with shares created via INSERT.

Fixes #1021 after merge.
[IMPROVED] Debug logging for purgeArchive calls
[FIX] use configured port for mysql connection
[FIX] enable Caching for  ExpectedNextDifficulty and NetworkExpectedTimePerBlock
added blocks until next difficulty change to EstNextDifficulty
added my own pool to POOLS.md
fixed links
[FIX] calculation
Merge pull request #1048 from Fredyy90/patch-4

added my own pool to POOLS.md
Merge pull request #1046 from Fredyy90/patch-2

[FIX] enable Caching for  ExpectedNextDifficulty and NetworkExpectedTimePerBlock
Merge pull request #1047 from Fredyy90/patch-3

added blocks until next difficulty change to EstNextDifficulty
Merge pull request #1044 from Fredyy90/patch-1

[FIX] use configured port for mysql connection
[UPDATE] Mention Markdown on Newspost creation
Undefined property: Notification::$mail

I'm not 100% sure this is a bug, but I'm getting the following error from my crons.

> PHP Notice:  Undefined property: Notification::$mail in /var/www/MPOS/public/include/classes/notification.class.php on line 158

> PHP Fatal error:  Call to a member function getError() on a non-object in /var/www/MPOS/public/include/classes/notification.class.php on line 158

It appears the `Notification` class extends the `Mail` class instead of `Base`, in which case `$this->mail` does not exist.
Merge pull request #1050 from headzoo/patch-1

Undefined property: Notification::$mail
Added one more Option to  "Ajax Data Interval", for better performance management
[FIX] fixed 3 Notices
Merge pull request #1051 from Fredyy90/patch-5

Added one more Option to  "Ajax Data Interval", for better performance management
Merge pull request #1053 from Fredyy90/patch-6

[FIX] fixed 3 Notices
[FiX] Division by zero warning on $dNetworkHashrate

When not connected to a wallet, the value of $dnetworkHashrate is set to 0, which causes a division by zero error.