Fix/graphics bugs

• Activate mipmap on MacOs to avoid Qt crashes
• Use 5.14.2 for Windows
• Request Qt 5.12 as a minimal version and cmake 3.9 (in order to embed big resources)
• Remove build on Debian8 as it has Qt 5.10
• Add default fonts for supported languages
• Use a build parameter to set dpiawareness (Windows)
• Add OTF support, in addition of TTF
• Explicit the answer to video request : Fix on not showing video when accepting a second request
• Use UTF8 when chatting and notifications to show all languages/symbols
• Fix SIP display on call view
• Fix a typo on a variable in call view (might lead to get transparent view)