Fix incorrect modification of bytea data when updating rows that contain bytea columns.
Based on the POC patch from ioguix.
This fixes SF Bug # 3243916.
fix typo
reword information around statistics collector. based on bug report SF #3602305
Add plugin hook 'head'.

Allows to add tags in <head /> from plugins
Add plugin hook 'logout'.

Allows to perform actions before beeing logged out.
Instantiate plugins AFTER connecting to the db.

This allows plugins to use the connection from their constructor if the
script created it, dpeending on $_no_db_connection global variable.
This revert commit b43084e022695d6b506799a1815fb4735bd57d13. I did a few
tests, mainly on intro page, but couldn't find the bug this commit tried
to fix...
plugin report: Remove non used global var in constructor.
Add try/catch blocks around plugin instanciation so they can throw an exception if needed.

This is usefull if a plugin don't want to start for some reasons.
Throwing an exception from the plugin constructors allows to remove this
plugin entirely during the script execution.
Instanciate $plugin_manager from login.php script if needed

This answers the question in commit message:
7d89d7cca40b5a8c3ac1874436630993f518410c. When the script require a
database connexion and the user must login, or in some cases of some
other related errors, we ar eincluding the login.php script and exit
immediatly. The login.php script requires the $plugin_manager, but it
is instanciated AFTER the connection codeblock (see commit 7d89d7cc),
leading to a FATAL error.
fixed a minor bug of Chinese UTF8 translation
change chinese translation of "null" and "empty"
Review/Update BUGS CREDITS HISTORY and TODO before release
Mark PPA release 5.1
Update/Fix History
Fix typo in variable name

It only concerns an fatal error message, no bad impacts
Cosmetic fix on Vacuum confirmation page for the "Freeze" checkbox

All other options checkbox have a space between the checkbox and their
label.
Completely udpate chinese utf8 according to english.
langcheck will give correct instruciton if the language parameter is added with php extension
Merge branch 'official'