V2.3.0

Issue #39 Additional updates for category 48, version 1.21
Issue #40 Example for reading Special Purpose field in CAT48
Issue #41 Implementing BDS decoding using fixed length definitions
Issue #42 Segmentation fault
Issue #43 Added hex dump of packets before asterix decoding in DEBUG mode
Issue #44 #45 CAT21v0.26 DI165 was defined as compound, changed to variable
Issue #46 filtering fails to properly produce valid json outputfiltering fails to properly produce valid json output
Issue #47 Fix: cat21v0.26/di090/PA is unsigned
Issue #48 Fix: cat21v0.26/160/GS is signed
Issue #49 Memory leaks fixedIssue #49 Memory leaks fixed
Issue #50 fixed spelling typo
Issue #51 BDS decoding implemented (for now registers 40,50,60)
Feature: Added automatic tests and Travis CI integration