Replace a few more logical operators

Changed all remaining uses of 'and' (T_LOGICAL_AND) and 'or'
(T_LOGICAL_OR) except those in includes/libs/lessc.inc.php.

In maintenance/generateSitemap.php, also slightly cleaned up
touched code:

* Inlined GenerateSitemap::init_path().
* Removed the redundant `$fspath && !is_dir( $fspath )` check.
* Return a nonzero exit code if wfMkdirParents() fails.

There are still uses of 'xor' (T_LOGICAL_XOR) in the following
files, which I left as-is:

* includes/Export.php
* includes/htmlform/HTMLCheckField.php
* includes/Autopromote.php
* maintenance/importDump.php
* maintenance/backup.inc

Change-Id: I73cb20da989e90b52782e7499f633debd5ad265d
Merge "Replace a few more logical operators"