Generating primitives for chart visualisation can be moved to a
paralell executed task that loads the chart, thus speeding up
initial visualization. This is not possible for e.g. PDF or print
targets, only for edit visualization. On fallback, the replacement
images of the charts are used which are metafiles and have less
quality as primitives, but load quicker.

Change-Id: I68caa9e1bec50832bce535b5f54633d53cdef037