8.1.0

• Optimization ofthe first call to zim::Archive::iterEfficient (@veloman-yunkan #724)
• Add some documentation to zim::writer::IndexData (@mgautierfr #727)
• Correctly catch and rethrow exception thrown in worker threads at creation (@mgautierfr #496 #748)
• Optimization of Entry::getItem() (@veloman-yunkan #732)
• Fix declaration of zim::setICUDataDirectory() (@MohitMaliFtechiz #733)
• Add zim::Archive::getMediatCount() (@mgautierfr #730)
• Make compilaton of examples optional (@mgautierfr #738)
• Add a CI for wasm (@mgautierfr #746)
• Make constructor of SuggestionItem public (@veloman-yunkan #740)