Fix documentation in Linker::formatTemplates.

Follow up to 265404d93cd99bf067064f947f5fc361f54466d7.
Make it clear that when a string is passed to the function,
it has to be already escaped. Also added Message as a
possible parameter type.

Change-Id: I4fb309d0dfcdf61b92c42db4b7ca2ea651d5f071
Mention that User::setInternalPassword() accepts null as password string

This allows to set an invalid hash preventing the user from logging in.

Change-Id: I8869eda42fd902dd26660c63e5f213b63e7e77ef
Merge "Mention that User::setInternalPassword() accepts null as password string"
Merge "Fix documentation in Linker::formatTemplates."