gui: fix lost changes for dye database autocompletion in merge

Rinze broke it in his merge bf16d87d0dfa8b5f4e4b2d8ba583e0e108b14e1a
gui comp: improve key handling in text autocompletion

left/right keys should work again
numpad enter == enter
simplify code
gui.util: improve LimitInvocation to not cancel timer

detect that a timer is already set (in the future) and trust it to run

also add a test case to validate the decorator
hdf5: fix format of some metadata to make Huygens happy

it seems pretty happy now
gui: slightly simplify some creations of VAConnectors