Miscellaneous changes before 8.x-1.0

Some of the test files contain calls to t(' ') in places where it should not be used. These are:

1. The message shown in the test output for each assertion call
2. Invented titles of test nodes
3. The readable name passed to drupalCreateContentType()

After the above have been removed this leaves just one place where we have t(' ') in our test files, this is in calls to drupalPostForm() and judging by the API docs and real core test examples it is ok to use it here.

This patch removes the calls in 1-3 above.

In hook_node_presave the isAllowed() 3rd-party hook should be called for unpublishing, not just for publishing.

Added test coverage to SchedulerApiTest.php

In many tests we had defined the node storage as $this->container->get('entity.manager')->getStorage('node');. However, it has also been a property created in SchedulerTestBase for a while, so this patch removes the repeated re-definitions and re-uses $this->nodeStorage instead.

This patch implements another two @TODOs in tests:

1. Use $this->nodetype, which is created in SchedulerTestBase, instead of re-defining with NodeType::load('page') in the test files.
2. Use $this->nodetype->get('name') instead of the hard-coded 'Basic page'.

Further tidy-up of test files and re-using properties for efficiency:

• change hard-coded 'page' to $this->type
• change $this->nodetype->get('type') to $this->type
• new protected $typeName for the string 'Basic Page' to avoid repeat hard-coding
• change $this->nodetype->get('name') to $this->typeName

The schedulerManager function runCron is better named runLightweightCron as that describes what it does.

Fixed typo in the function call.

In 7.x Scheduler implemented hook_scheduler_api() which allowed other modules to react to Scheduler publishing or unpublishing content. In 8.x we have events, so any implementations of this hook will be ignored and should be replaced by event listeners. This patch gives a warning in the dblog if any third-party modules still try to implement hook_scheduler_api() in their 8.x code.

Slight text changes to the status report.

Improved messages and text in API test module

Scheduler 8.x-1.0 was released on 14th November 2017. All of the commits above (apart from the last one in #25 updating the Travis testing core version) were in for 8.x-1.0 hence renaming and marking this issue fixed.