Bug 15655 – SysTime.from*String incorrectly accept single digit time zones and minutes > 59

"+08" and "-08" would be valid for a time zone per ISO 8601, as should be "+08:00" and "-08:00" for the extended format and "+0800" and "-0800" for the non-extdended format. However, strings like "+8" or "-8" are not legal. It must be +hhmm, -hhmm, +hh, or -hh for non-extended and +hh:mm, -hh:mm, +hh, or -hh for extended. And currently, SysTime.from*String is not properly strict about the time zone, allowing +h and -h when there are no minutes (even though it is properly strict when there are minutes) and is not strict about the number of digits in the minutes. In addition, it is not strict about whether the number of minutes is actually valid (e.g. "+07:60" should not be valid).

Commit pushed to master at https://github.com/D-Programming-Language/phobos https://github.com/D-Programming-Language/phobos/commit/0faa191fc80dc3d0e67de5f5e83bd805c2eab794 Fix issue# 15655. SysTime.from*String accepted single digit time zones and minutes > 59, which is against the ISO standard. This commit fixes that.