improved initialization of matching exercises, display of exercise parameters and fixed a bug in the exercise list

preview page now uses the current language for H5P exercises instead of the browser default language

fixed regex in the ShowText page which caused firefox to break (no lookahead/lookbehind allowed in firefox regex)

minor fixes to text range (no unnecessary API calls) and vocabulary check (update corpus display after corpus change)

# Conflicts:
#	package-lock.json

texts in the vocabulary check are now precisely identifiable and will be cached, replacing the major base text

test module now has new improvements in: timer, navigation, better rounding for evaluation percentage