Wrap CMAKE_SHARED_LIBRARY_CXX_FLAGS in quotes.

The variable is empty on some platforms (Windows), would cause issues.
Don't use `this->` when it's not explicitly necessary.

Makes code more readable and less ambiguous.
Oh hey, I have Twitter!
Interconnect: forgotten else.

The second branch was executed after the data were deleted, thus
accessing invalid memory. However the assertion fired only on Windows
and not on my Linux box, causing this HUGE error to be unnoticed for a
long time.
Utility: don't use std::u32string on Windows.

Currently Windows == MinGW, but as Visual Studio doesn't have Unicode
literals or anything depending on them, this would work there too. Using
std::vector<char32_t> instead, because MinGW (GCC 4.7.2) weirdly fails
while freeing memory after std::u32string. Hopefully this will get fixed
in future releases, as this is PITA to maintain.
Utility: various cleanup.
Utility: added Endianness::*EndianInPlace() convenience function.
Containers: ArrayReference specialization for const void.

The original implementation cannot be used for this (voids are much more
restrictive). Will be useful for passing untyped data to external
libraries.
Containers: better documentation.

Victim of copypaste.
Mention CORRADE_GCC47_COMPATIBILITY CMake variable in docs.
Mention GCC4*_COMPATIBILITY CMake options, reword the docs a bit.
Properly document Windows building.
Minor formatting changes.
UseCorrade.cmake: check compiler version and error out if not supported.
package: updated corrade-git ArchLinux package.
Updated ArchLinux building documentation.
UseCorrade.cmake: more improvements to compatibility mode checker.

Check also that newer unsupported compiler isn't used and fix the
building (the variables were defined after UseCorrade.cmake was
included).
UseCorrade.cmake: check also for compatibility mode for older compilers.

This mode is available only in compatibility branch, but in most cases
UseCorrade.cmake from master is used along it, so it's good to have it
here too.
Sort compiler compatibility modes in descending order.

More users are interested in compatibility with more recent compilers,
so make them first.
PluginManager: documentation fixes.