Add (even more) radio flux frequencies #157
Description
As a follow on to #111/#113, @BordeauxDave has noted (via email) that more radio flux frequencies now exist in the catalogue. psrqpy currently does not have any of the following radio frequency values:
S327
S820
S944
S1429
S1625
S1284
S1300
S1700
S2100
S2600
S3300
S3800
S1500
S2250
S8600
S155
S816
S1558
S2612
S4988
S5012
S8488
S9512
S430
S1380
S35
S64
S79
S9000
S1283
S1284
which are in the catalogue. These should be added.