implemented support of sessions in the client
started view services implementation
Browseing compiles but tests fail
tested Borwse requests
added mask for bits of NodeID encoding  value.
Command line tools: added browsing of nodes by two byte and string IDs.
Implemented reading attributes and tests
added reading of attributes to the opca tool
implemented write
updated variant in the opcua mappings
added constructors for vairant
implemented write operation in opcua command line tool
updated 'make dist' target
Merge branch 'master' into development