Whitespace, code layout and guidelines
Code cleanup in bug_report.php

- Move $f_rel_type init to where others form vars are set
- Remove duplicate initialization of form variable $f_master_bug_id
- Use defined $t_project_id instead of $t_master_bug->project_id
- Replace hardcoded numbers with relationship constants
Allow Reporters to Clone issues

Previously, users needed to have update_bug_threshold to be able to
clone issues, since the creation of a relationship with the parent bug
requires to update it.

This patch lets Reporters clone issues and allows them to create a
relationship with the parent, even if they lack updater access.

Fixes #11290 (implements option 3)
Correct comparison operator
Allow Reporters to Clone issues

Pull request #130