allow to directly use node definitions in precedence operators

like

tok . pos="NN"

instead of

tok & pos="NN" & # 1 . #2
do not use multimap for nodes since variable names are only allowed once per alternative
use "==" operator for identiy in order to solve ambiguity when parsing

tok="abc" . node

which could be either

tok="abc" & node & #1 . #2
or
tok & "abc" & node &  #1 = #2 & #2 . #3
Merged 'develop'.
avoid null pointer exception when debugging with inspect(...)
use a separate map of token positions for each alternative
adding a new good test query
fixing failed tests: we did not count the node ids correctly when local map was used
implement/fix #255 (AQL shortcut: allow to write operators directly between node definitions)
fix compilation error
do not throw exception on invalid input
do not throw exception when there is no result
use a CSSLayout instead of a VerticalLayout for the ControlPanel in order to avoid the extra space problem
lighter div-structure in ExampleQueriesPanel
do not throw error when double clicking on a corpus browser annotation entry
last fix for unneeded scrollbar caused the corpus table scrolling to be disabled. the real "reason" for the extra scrolling was a margin setting in vaadin
don't enforce streaming when websockets are available
allow unknown fields in the instance JSON files
adding a helper class to controll polling during an UI.access call
making the poll time functions private and provide an API to run Jobs in the background instead