Bugfix: interpret commandline parameters as utf-8

fixes #1293
Merge branch 'master' into next
Merge branch 'fix-i3-save-tree-unicode-args'
libxkbcommon 0.4.0 is required, 0.2.0 is too old (Thanks Mii)

fixes #1295
cleanup: src/i3.mk: add XKB_COMMON_CFLAGS when compiling i3
Bugfix: create the directory for storing the restart state (Thanks hjem)

fixes #1303
Merge branch 'fix-restart'
Merge branch 'master' into next