travis doxygen fixes
harmonize table layout in docs
last call for pretty tables
getting doxygen 1.8
getting doxygen 1.8
Merge branch 'master' of https://github.com/acplt/open62541

Conflicts:
	.travis.yml
Functions UA_Variant_borrowSetValue and ..Array

This allows to define variants whose payload will not be deleted.
It is achieved by a second vtable. This functionality can be used
e.g. when UA_VariableNodes point into a "father" structured object
that is stored in an UA_VariableNode itself.
small code cleanups
Ensure that UA_INVALIDTYPE has the largest id

So that we can differentiate between "good" and "bad"
types by ony giving an upper limit.
E.g. if(type_id <= UA_DIAGNOSTICINFO_NS0) ...
documentation structure