Update to API version 5.2

[njahn82]

Probably, synonym param needs to be changed:

The parameter “synonym” for the methods “searchPublications” and “profilePublications” has been changed from Boolean to String. The default value is “false” as before. The parameter “synonym” accepts the same values as “inlineImages”, the valid values are “y”, “yes”, “true”, “n”, “no” and “false”.

Due date: 10 May