clang-analyzer: Fix dead stores in window.c.
clang-analyzer: Reduce scope in spell.c.
clang-analyzer: Reduce scope in screen.c.
clang-analyzer: Reduce scope in search.c.
clang-analyzer: Reduce scope in arabic.c.
clang-analyzer: Reduce scope in syntax.c.
clang-analyzer: Fix dead stores in garray.c.
Merge pull request #985 from fwalch/clang-analyzer-dead-assignments

Clang analyzer: fix dead stores / reduce scope
Implement `os_mkdtemp` on top of `uv_fs_mkdtemp`
documentation: Update tempfile and tempname()
Merge pull request #1034 'Implement `os_mkdtemp` on top of `uv_fs_mkdtemp`'
build/test: setup functional tests using vroom
build/test: setup vroom installation on travis