Add/improve end-to-end tests.
• Add CTIerrorBegin/End call to a CTIerrorContinued call site that was missed in an earlier commit. • Add end-to-end test for CTIerrorBegin/Continued/End. • Rename error end-to-end tests to have consistent naming. • Expand test-error-generic to additionally test line wrapping and custom header arguments. • Fix inconsistent CTIerror behaviour by moving the CTFinitialize call from OPTcheckOptionConsistency to main.c.