Add #pragma clang diagnostic push to allow generally stricter checks
Mark several const variables only used in their own .m files static
Address stricter compiler warnings by making trivial changes
Fixed a bug in Example app
Fix getter for progress in MRProgressOverlayView
Turn on hard mode

With some minor restrictions.
Fixed unsafe floating-point type comparisons
Removed wrong attribute
Ignore "-Wassign-enum" for `options:0`
Added -Wno-gnu to use MIN, MAX, ABS macros
Fixed `pod lib lint` warnings
Fixed warning because of unused var if NS_BLOCK_ASSERTIONS is enabled

The warning was:
"MRMethodCopier.m:27:10: warning: unused variable 'success' [-Wunused-variable]"
This happens because CocoaPods sets as a default build setting 'NS_BLOCK_ASSERTIONS'.
Fixed .travis.yml
Merge branch 'master' into fix/53_compiler_warnings
Fixed warning from missing cast
Merge pull request #56 from mrackwitz/fix/53_compiler_warnings

Fix #53: Stricter compiler warnings
Fixes #57: Hides overlay if task/operation is finished
Added accessibility labels, hints and values
Allow to escape from MRProgressOverlayView
Ensure that value label text is initially set to 0%