security/core#14 Validate "context" inputs

security/core#14 Validate "context" inputs

When "context" is passed as a GET parameter, ensure that its values is
a valid "Alphanumeric" type. This helps prevent XSS when the "context"
value finds its way into templates that lack HTML output encoding.

Replace...

    CRM_Utils_Request::retrieve\((['"])context\1,(\s*)(['"])String\3

...with...

    CRM_Utils_Request::retrieve\($1context$1,$3Alphanumeric$3

Also search for the following and manually fix:

    \$_GET\[(['"])context\1\]
    \$_POST\[(['"])context\1\]
    \$_REQUEST\[(['"])context\1\]