Squashed 'libsrcs/libRocket/libRocket/' changes from 96d91c3..eee0de5

eee0de5 Merge remote-tracking branch 'remotes/czbming/official'
f13eede Fix pointer conversion bug in Variant
21c826b Fixed memory leaks and copy paste error in ElementTabSet
2108885 Merge remote-tracking branch 'remotes/origin/fixwarnings'
1606ea3 Merge remote-tracking branch 'remotes/lloydw/master' into kerning_footprint_reduce
fa07b1e Do not precalculate kerning for all characters
4b4dd28 More fixes for compilation warnings
e3033ad Move ElementStyleCache.* to Core
69feff3 Fix gcc compilation warnings

git-subtree-dir: libsrcs/libRocket/libRocket
git-subtree-split: eee0de5a962b67544d568e64d95485721449ca98
Merge commit '031aeba4b33c3286ffb70f045e2710731249c774'