Fixed language codes in Metadata Syntax doc.
Fixed default ini language value.
Fixed Nehrim defaults, game settings generation.
Sorted out language handling.

"Any" is now only valid when choosing message content.
The API no longer requires libgit2 when built.

It wasn't used in the code, and this means that Windows XP support can
be retained in the API while also allowing it to be dropped in the
application when libgit2 is updated.
Updated libgit2 usage for v0.21.0.
Removed Windows XP support from CMakeLists.

Also updated readme and build instructions.
Updated build instructions, changelog.

It seems that CMake 3.0.0's GUI sets the toolset to `vc120_xp` by
default, and it can't then be overridden in a CMakeLists.txt. Generating
using the command line is therefore more reliable.
Various C++11-related changes.

* Switched to standard libraries for regex, unordered_map and
unordered_set.
* Switched to using the C++ syntax for C header includes (eg. `cstdint`
rather than `stdint.h`).
* Replaced IntToString with STL's to_string.
More C++11 changes.

* Made a few standard library replacements missed in the API.
* Swapped in the range syntax with the auto keyword in for loops where
appropriate.
NULL -> nullptr switch.
Next release will be 0.6.

Removal of Windows XP support warrants it.
Exception handling for saving settings.

Should fix issue #174.
Added plugin counts to report summary.

Also split the summary up into version info and plugin & message count
sections.
Added find dialog to report viewer.

Closes #175.
Implemented delete-and-retry for masterlist update.

Closes #176.
Whoops, was freeing the same memory twice.
Refactored editor code.

Now the editor is a panel. Dialog and frame classes add it to window
content, and handle exit behaviour.

The code compiles, but is currently untested and definitely won't work
properly for sorting.
Fixed false positive plugin highlighting in editor.

This was an existing issue, unrelated to code refactoring, wherea plugin
selecting a plugin could bold the previous plugin's list entry even if
no changes were made. Also fixed incorrect priority values being
displayed on initialisation.
Finished implementing new editors.

* Fixed crash due to uninitialised mini editor content.
* Sorting now rearranges rather than replaces the existing plugin list
(yay lambda function!).
* During the sorting process, plugin data is stored in the plugin list,
as the graph is now a temporary object confined to the sorting loop.
* Userlist merging, condition eval and validity checks are deferred to
within the sorting loop.