Add documentation about the script and regex linter to the user guide.

Summary:
The big, gigantic comment about the script and regex linter belongs in a more obvious place.  I think this is a more obvious place. I also cleaned up a couple things.

I'll update D9084 to remove the big comment block and point here instead.

Test Plan: `bin/diviner generate --book src/docs/book/user.book`

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9100
Remove `shouldCreateDiffusionRequest` from Diffusion conduit methods

Summary:
Ref T2683. This has no callsites, and the functionality is covered by the `initFromConduit` flag.

This simplifies the code and reduces then number of internal `diffusion.resolverefs` calls we make on, e.g., the Git repository page from 7 to 2.

Test Plan: Grepped for these symbols.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T2683

Differential Revision: https://secure.phabricator.com/D9090
Rename "stableCommitName" to "stableCommit"

Summary:
Ref T2683. This is closely related to "symbolicCommit", but has an inconsistent "name" on the end.

Also, `diffusion.searchquery` uses this parameter inconsistently.

Test Plan:
  - `grep`ed for callsites.
  - Ran searches in Git and Mercurial repositories.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T2683

Differential Revision: https://secure.phabricator.com/D9091
Rename "commitType" to "symbolicType"

Summary:
Ref T2683. The old name was a bit confusing because it meant "the type of the thing the symbol represents": a "commit type" should logically always be "commit".

(Currently, this is only used to detect when we're looking at a tag.)

Test Plan: Looked at a tag. Looked at some other non-tag things. Browsed around, `grep`.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T2683

Differential Revision: https://secure.phabricator.com/D9092
Let diffusion.readmequery accept a commit

Summary:
Ref T2683. This should probably just be `diffusion.filecontentquery` but keep things as they are for now.

This method uses a commit, so accept one. Soon, this will save a bit of work.

Test Plan: Viewed readmes in main and browse views.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T2683

Differential Revision: https://secure.phabricator.com/D9093
Throw a more tailored exception after failing to resolve a ref

Summary: Ref T2683. Throw a more tailored exception to allow callers to distinguish between bad refs (which are expected, if users try to visit garbage branches) and other types of errors.

Test Plan: Tried to view branch "alksndfklansdf". Viewed branch "master".

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T2683

Differential Revision: https://secure.phabricator.com/D9094
Improve clarity of commit and symbol handling in DiffusionRequest

Summary:
Ref T2683. Currently, DiffusionRequest has four different "commitey" things:

  - `commit`
  - `rawCommit`
  - `symbolicCommit`
  - `stableCommit`

Of these, only two are actually distinct, useful values: `symbolicCommit` (which holds the value the request originally contained, if one existed) and `stableCommit` (which resolves that value, or the value implied by its omission, into a stable, permanent commit identifier).

  - `rawCommit` is equivalent to `symbolicCommit` and can be simply removed.
  - `commit` has some sketchy magic around it that needs to be pulled out before it can be jettisoned.

Test Plan: Viewed SVN, Git, and Mercurial repositories. Viewed brwose/history/change/tag/branch/etc views.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T2683

Differential Revision: https://secure.phabricator.com/D9098
Remove `commit` from DiffusionRequest

Summary: Ref T2683. This field is //almost// entirely redundant with `symbolicCommit`. Improve how some of the diff query stuff works a bit, then remove it.

Test Plan: Browsed around in all interfaces, looked at a bunch of diffs, etc.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T2683

Differential Revision: https://secure.phabricator.com/D9099
Move Push log rendering to SearchEngine

Summary: Ref T4986. Move push logs to a View, then have all the stuff that needs to use it use that View.

Test Plan: Viewed push logs and transaction detail in Diffusion. Created a panel.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T4986

Differential Revision: https://secure.phabricator.com/D9104
Add a SublimeText-style repository typeahead

Summary:
Allows you to quickly search for files within a repository. Roughly:

  - We build a big tree of everything and ship it to the client.
  - The client implements a bunch of Sublime-ish magic to find paths.

Test Plan: {F154007}

Reviewers: chad, btrahan

Reviewed By: btrahan

Subscribers: epriestley, zeeg

Differential Revision: https://secure.phabricator.com/D9087
Git did not 3-way merge this quite correctly.
Use "added a dependency" over "added a revision"

Test Plan: Added a dependency, saw a descriptive description.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9111
Merge branch 'master' of github.com:facebook/phabricator