This commit removes the various compiler-specific JUCE_DEPRECATED macros and replaces them with C++14's deprecated attribute. It also removes the JUCE_CATCH_DEPRECATED_CODE_MISUSE flag as we can rely on the override specifier catching usage of these old virtual methods, and tidies up the DOXYGEN preprocessor checks as they were inconsistent across the codebase.

This fixes warnings that are emitted when building with the `-analyze`
flag enabled.

Previously, if `stopTimer()` was called from within
`hiResTimerCallback()`, a call to `isTimerRunning()` immediately
following the call to `stopTimer()` would return true instead of false.

This patch fixes the issue, and adds some tests to verify the new
behaviour.

Please see the forum post "Re-structuring of JUCE’s low-level Android code" and the BREAKING-CHANGES.txt for more information.