Add pre_changelog and release_changelog commands

[wilzbach]

Follow-up to #1817 and #1821

The idea is the more logic we move to the same spot, the easier it gets to update it and improve it.
Also if we can try out the script that Martin runs, the less likely it is for us to break them in the future ;-)

Eventually the plan is to generate the _pre.dd pages automatically, but this depends on dlang/tools#251

[dlang-bot]

Thanks for your pull request, @wilzbach!

Bugzilla references

Your PR doesn't reference any Bugzilla issue.

If your PR contains non-trivial changes, please reference a Bugzilla issue or create a manual changelog.

[wilzbach]

@MartinNowak release_changelog should be a drop-in replacement for whatever you are currently using. It's a bit different though. Are you using the newest version at tools?

diff --git a/changelog/2.074.1.dd b/changelog/2.074.1.dd
index f1e38b17..f497c8ce 100644
--- a/changelog/2.074.1.dd
+++ b/changelog/2.074.1.dd
@@ -2,17 +2,13 @@ Ddoc
 
 $(CHANGELOG_NAV_LAST 2.074.0)
 
-$(VERSION May 30, 2017, =================================================,
+$(VERSION July 15, 2017, =================================================,
 
-$(BR)$(BIG $(RELATIVE_LINK2 bugfix-list, List of all bug fixes and enhancements in D $(VER).))
-
-$(HR)
-
-$(BR)$(BIG $(LNAME2 bugfix-list, List of all bug fixes and enhancements in D $(VER):))
+$(BR)$(BIG List of all bug fixes and enhancements in D $(VER).)
 
 $(BUGSTITLE DMD Compiler regressions,
 
-$(LI $(BUGZILLA 17407): [REG] __traits$(LPAREN)compiles$(RPAREN) triggers assertion failure)
+$(LI $(BUGZILLA 17407): [REG2.067] __traits$(LPAREN)compiles$(RPAREN) triggers assertion failure)
 )
 $(BUGSTITLE DMD Compiler bugs,
 
@@ -20,6 +16,7 @@ $(LI $(BUGZILLA 17289): With Xcode 8.3 linker, warnings of "pointer not aligned"
 )
 $(BUGSTITLE Phobos regressions,
 
+$(LI $(BUGZILLA 17264): [REG2.073] uniq fails with const elements)
 $(LI $(BUGZILLA 17330): [REG 2.072] BigInt's constructor used to be pure)
 $(LI $(BUGZILLA 17340): [REG 2.074.0] isNumeric!bool should not be true)
 )

[CyberShadow]

intended*

[MartinNowak]

In my experience any integration into dlang.org's Makefile was always a pain to work with as it's taking a role as central build script, thus doesn't integrate well with an outer build script (e.g. starts to clone and/or build random random stuff).
Here is how I currently generate the changelogs which looks fine.
https://gist.github.com/MartinNowak/a471fe7ddbfeef205cdf04c93a94c6d0#file-release-sh-L61
Might make sense to add this as makefile rule, but it's already release_changelog -> html -> $(ALL_FILES) -> dmd again, not the most stable approach for (semi-)automation.

[MartinNowak]

I'd rather revert #1817 for now, even though it contained some useful changes, and integrate the discussion and all related changes into #1821 (comment). Also slightly reducing the confusion of half a dozen of PRs.