[doc] Update tutorial examples to use the parameter builtin

[vkarak]

Also add an example that shows the RegressionMixin.

Addresses #1691.

[jgphpc]

Suggested change: tutorial_basics.rst line 73:

Finally, a test must either define an executable

I would move this part before the part about sanity:

Each regression test must always define

[jgphpc]

tutorial_basics.rst, line 131: add

(you can control this through the --keep-stage-files command-line option)

or

(see reframe --help)

?

[jgphpc]

typo in line 641 of tutorial_basics.rst

wee convert that to

at the same time (line 757) sent

and the same time being send to Syslog

[jjotero]

I've spotted two other uses of the word parameter which might be misleading, since they do not refer to the parameter built-in. They're both in tutorials_basic:

• Line 59: Rename parameter to variables. Also, the sentence in this line is now a bit obsolete, since the user can just define the variables directly in the class body.
• Line 1065: I'd just remove the word parameters.

[jgphpc]

tutorial_basics.rst, line 798, typo: in order to access

tutorial_advanced.rst, line 166, typo: coniguration

tutorial_advanced.rst, line 214, typo: proceed

[vkarak]

(see reframe --help)

I don't want to put too many details in the tutorial.

[jjotero]

lgtm