remove base_kernel_url
don't use combine option on ucs package

Caused problems with unicode.

It seems f9c32fcee337b6560ec31e25fba04cae6021b74a was actually the right fix for the original error, not faf51b858a8c5757944822ee1d75c11367e994f.

closes #5129
Some template static_url tweaks

- don't try to include version in static_urls that don't point to files
- use full static_urls (with extension) for backbone and underscore, so version can be computed

closes #5141
Simplify implementation of TemporaryWorkingDirectory.

Closes gh-5160
Merge pull request #5133 from minrk/latex-unicode-nightmare

Don't use combine option on ucs package

**never** use combine when mixing ascii and non-ascii chars or all the non-ascii chars will be rendered after the ascii one have been.
remove mktemp usage

mktemp is insecure, by the time the generated filename is used someone
else might have modified it.
Merge pull request #5166 from juliantaylor/mktemp-remove

remove mktemp usage
Merge pull request #5163 from takluyver/i5160

Simplify implementation of TemporaryWorkingDirectory.
Merge pull request #5100 from minrk/base_kernel_url

remove base_kernel_url
Merge pull request #5147 from minrk/static-url-version

Some template URL changes