1.8.1 dev string length

Limiting deserialized string lengths for alerts and strings from nodes. 

Class LimitedString as LIMITED_STRING(obj,size); was tested by artificially shortening the alert.h LIMITED_STRING lengths to 4, and running the alert_tests boost unit test.  Truncated alerts appeared limited to 4 bytes as we wanted/expected.  Alert lengths, of course, were returned to the default 256 after the test.