CLSA-2026-1777540266 vim: Fix of 10 CVEs

CVE-2022-2182: in doonecmd, after ";" sets curwin-wcursor.lnum to ea.line2, call checkcursor instead of checkcursorlnum so the column is validated too, and fall back to checkcursorcol when ea.line2 is zero, preventing read past end-of-line on ":0;'". - CVE-2022-2206: in checkshellsize, clamp...