Expand Remarkup interpreter block capabilities a little bit

Summary:
Ref T3274. Ref T3591. Ref T3964. Allows interpreters to access the engine so they can check for text mode, grab the viewer/config, etc.

Also, make the unit tests not depend on trailing whitespace to pass.

Test Plan: See next revision.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T3274, T3591, T3964

Differential Revision: https://secure.phabricator.com/D7331
Be more liberal about whitespace in the "interpreter block" rule

Summary: Currently, we require `x (y) {{{z}}}`. Permit less whitespace, `x(y){{{z}}}`.

Test Plan: Unit test.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D7338
Allow concatenating HTML with operator extension

Summary: This will prevent double escaping.

Test Plan: New test case.

Reviewers: epriestley

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Differential Revision: https://secure.phabricator.com/D7347
Implement `setEnv`.

Summary: Implements `setEnv` on `ExecFuture` so that the environment variable can be set.

Test Plan: Completely untested.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Differential Revision: https://secure.phabricator.com/D7396
Format conduit call information in ServiceProfiler

Summary: Mabye some day this will be pluggable. For now, add an entry to the big switch. See D7482.

Test Plan: Looked at "Services" tab.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Differential Revision: https://secure.phabricator.com/D7483
Add "PhutilDirectedScalarGraph"

Summary: Ref T4068. I need a non-fancy version of this to topographically sort commits.

Test Plan: See next revision.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T4068

Differential Revision: https://secure.phabricator.com/D7517
Merge remote-tracking branch 'upstream/master'