match accented chars in ::findText()

when !caseSensitive is passed and the search term is pure Ascii.

This makes possible that simple ascii search terms can match on
their accented and other diacritics counterparts.

Issue #637
6 jobs from ascii_simple_search in 28 minutes and 43 seconds (queued for 2 minutes and 46 seconds)
Status Job ID Name Coverage
  Build
passed #57983
build

00:05:22

passed #57988
build_android

00:01:07

passed #57984
build_clang_libcpp

00:05:14

passed #57987
build_clazy

00:04:13

passed #57985
build_gcc_49

00:08:37

passed #57986
build_mingw64_fedora

00:04:07