[FIX] XQuery: only bind context before compilation. Fixes #934
Merge branch 'stable'

Conflicts:
	basex-core/src/main/java/org/basex/query/QueryContext.java
	basex-core/src/main/java/org/basex/query/QueryParser.java
	basex-core/src/main/java/org/basex/query/func/JavaMapping.java