generating predictions can fail when there's a mismatch between frequency and pattern regularity

[Galen Charlton]

Consider a serials predication pattern whose code is this:

["0","0","8","1","a","v","b","no","u","10","v","c","i","(year)","j","(month)","w","m","y","pd01","y","cm06/07","y","cm12/01"]

Although the frequency is monthly ($w = m), a pattern regularity value of $y = pd01 cause it to try to advance a day rather than a month when generating new predications, leading the alternate serials interface to hang.

There is also an associated crash like this:

Error: Error: Method error: undefined : *** Call to [open-ils.serial.make_predictions] failed for session [0.417711228733259171455731202854], thread trace [0]:
The 'day' parameter (undef) to DateTime::new was an 'undef', which is not one of the allowed types: scalar
 at /usr/lib/perl5/DateTime.pm line 199
 DateTime::new(undef, 'year', 2015, 'month', 12, 'day', undef) called at /usr/local/share/perl/5.14.2/OpenILS/Utils/MFHD/Date.pm line 73
 MFHD::Date::subsequent_day(01, 'ARRAY(0x45d9988)', 'MFHD::Caption=HASH(0x49b1648)') called at /usr/local/share/perl/5.14.2/OpenILS/Utils/MFHD/Caption.pm line 433
[snip]

Such a pattern is very likely a mistake, but attempt to use it should present a more useful error message.

Evergreen 2.9 (probably master)