Release: 6.0.0rc0 (#846)

* Add release date to changelog

* Add support for prerelease section in version

* Bump version for 6.0.0rc0 release

* Update release date

Author: mdickinson

CHANGES.rst

@@ -4,7 +4,7 @@ Traits CHANGELOG
 Release 6.0.0rc0
 ----------------
 
-Released: XXXX-XX-XX
+Released: 2020-01-30
 
 Release notes
 ~~~~~~~~~~~~~

setup.py

@@ -22,16 +22,17 @@
 MAJOR = 6
 MINOR = 0
 MICRO = 0
-IS_RELEASED = False
+PRERELEASE = "rc0"
+IS_RELEASED = True
 
 # If this file is part of a Git export (for example created with "git archive",
 # or downloaded from GitHub), ARCHIVE_COMMIT_HASH gives the full hash of the
 # commit that was exported.
 ARCHIVE_COMMIT_HASH = "$Format:%H$"
 
 # Templates for version strings.
-RELEASED_VERSION = "{major}.{minor}.{micro}"
-UNRELEASED_VERSION = "{major}.{minor}.{micro}.dev{dev}"
+RELEASED_VERSION = "{major}.{minor}.{micro}{prerelease}"
+UNRELEASED_VERSION = "{major}.{minor}.{micro}{prerelease}.dev{dev}"
 
 # Paths to the autogenerated version file and the Git directory.
 HERE = os.path.abspath(os.path.dirname(__file__))
@@ -171,7 +172,11 @@ def git_version():
     git_count, git_revision = _git_info()
     version_template = RELEASED_VERSION if IS_RELEASED else UNRELEASED_VERSION
     version = version_template.format(
-        major=MAJOR, minor=MINOR, micro=MICRO, dev=git_count
+        major=MAJOR,
+        minor=MINOR,
+        micro=MICRO,
+        prerelease=PRERELEASE,
+        dev=git_count,
     )
     return version, git_revision
 
@@ -197,7 +202,11 @@ def archive_version():
 
     version_template = RELEASED_VERSION if IS_RELEASED else UNRELEASED_VERSION
     version = version_template.format(
-        major=MAJOR, minor=MINOR, micro=MICRO, dev="-unknown"
+        major=MAJOR,
+        minor=MINOR,
+        micro=MICRO,
+        prerelease=PRERELEASE,
+        dev="-unknown",
     )
     return version, ARCHIVE_COMMIT_HASH