BUG: Right click on LeftAndMain menu caused CMS preview window to open

The onclick event for LeftAndMain menu links didn't check if the click
was left or right, meaning that right click events could trigger the
function for loading split view mode in some browser/os combinations.
Clarified docs on isDev usage in dev/build
FIX PHPUnit latest not working with composer installed builds

When using composer, we must rely on the composer autoloader to
load in PHPUnit and not try do to so ourselves, as the old
PHPUnit\Autoload.php file doesnt understand how to find things
in vendor
Merge pull request #1117 from silverstripe-rebelalliance/fix/phpunit/3.0

FIX PHPUnit latest not working with composer installed builds
Fix typo in templates/Controller.ss
BUG Exception handling and email notification mechanism now correctly considers the stacktrace as provided by the exceptionHandler function, instead of attempting to perform a debug_backtrace further down the reporting chain (which ends up generating an unnecessarily nested stacktrace). Debug was cleaned up so that errorHandler and exceptionHandler both act consistently. As a result, the LogErrorEmailFormatter class could be simplified.

This was required to fix a bug in which exceptions would not have a visible stacktrace when handled by the email logger.
Added test cases for exception error logging
Document that yaml files shouldnt be served directly
Include code to block yaml files in installer generated .htaccess
MINOR Formatting fix
Merge pull request #1141 from drzax/patch-1

MINOR Formatting fix
Merge pull request #1140 from silverstripe-rebelalliance/yamlaccess_30

Document that yaml files shouldnt be served directly
Update docs/en/changelogs/3.0.0.md

minor typo
BUGFIX: for date manipulation use the SS_Datetime::now, otherwise it does not respect the mock date.
NEW: Allow configuration of send_all_emails_to, ccs_all_emails_to, and bcc_all_emails_to via the config system.
NEW: Added Email::send_all_emails_from() setting.
FIX: Set up the test mailer before loading the fixture, in case fixture-creation causes emails to be generated.
FIX: Fixed operation of inlined images in Mailer, when no inlined images actually attached.
API CHANGE: Added Security::set_login_url() so that you can define an alternative log-in page if you have made one yourself.
BUGFIX: Improved detection of empty HTMLText fields.