updated to 7.4.884

updated to 7.4.884

7.4.874  MS-Windows: size isn't right when inside another application
7.4.875  not obvious how to contribute
7.4.876  Windows7: using vim with msys/msys2, conhost.exe freezes
7.4.877  ":find" sometimes fails
7.4.878  Coverity error for clearing only one byte of struct
7.4.879  can't see line numbers in nested function calls
7.4.880  no build and coverage status
7.4.881  (after 7.4.879) test 49 fails
7.4.882  popup menu remains visible when leaving command line window
7.4.883  (after 7.4.818) block-mode replace works characterwise
7.4.884  Travis also builds on a tag push