[ADD] XQuery: Dynamic Updating Function Invocation. Closes #939
[MIN] URI Tests deactivated (#928)
Merge branch 'stable'

Conflicts:
	basex-core/src/main/java/org/basex/query/QueryParser.java
	basex-core/src/main/java/org/basex/query/func/FuncLit.java
	basex-core/src/main/java/org/basex/query/func/Functions.java
[FIX] XQuery: minor fixes conc. updating function items