Remove set_include_path() calls

Since we know the full path to the files being included, it is not
necessary to change the include path.

Fixes #11549
Fixes #17186: Remove  in favor of MantisTouchRedirect plugin.
Fixes #17185: Read-only access via soap api should be available to VIEWER level.
Fixes #17233: Fix the license in the SOAP API file headers

The SOAP API file headers still reflect the license from the time the web service was part of the MantisConnect product.

I've contributed the web service to MantisBT and hence it should honer the same license when distributed with MantisBT.
Oracle: fix ORA-01442 error during installation

Oracle does not allow to add a NOT NULL constraint if it's already
present; it will just keep the existing constraint if a column is
altered without mentioning NOT NULL. MySQL on the other hand will
actually remove the constraint if NOT NULL is not specified again.
Fix PHP warning in db_table_exists()

If db_get_table_list() does not return an array, PHP will issue a
'Invalid argument supplied for foreach' warning.
HTML API: revise order of elements in HEAD section

The HTML specification [1] does not specify a strict order for the
elements within the HEAD section, other than Content-Type appearing
within the first 1024 bytes of the document.

Microsoft / Internet Explorer has stricter guidelines when it comes to
defining compatibility mode [2]: "The X-UA-Compatible header [...] must
appear in the header of the webpage (the HEAD section) before all other
elements except for the title element and other meta elements."

This commit reorganizes html_page_top1() function to:
- define Content-Type as the HEAD's first element
- allow users to set X-UA-Compatible in $g_meta_include_file
- include CSS after defining the TITLE, together with other LINK tags

Fixes #17176

[1] http://www.w3.org/TR/html5/document-metadata.html
[2] http://msdn.microsoft.com/en-us/library/jj676915%28v=vs.85%29.aspx