release-notes: use CHANGELOG.md

Add a file CHANGELOG.md in the root Subsurface directory
and track this file with the `-text merge=union` attribute.

This prevents merge conflicts if release notes are added
on top of the file by different commits.

Also, make ReleaseNotes/ReleaseNotes.txt point to that file.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>

.gitattributes

@@ -5,3 +5,4 @@ theme/jqplot.canvasAxisTickRenderer.min.js binary
 theme/jqplot.highlighter.min.js binary
 theme/jquery.jqplot.min.js binary
 theme/jquery.min.js binary
+CHANGELOG.md -text merge=union

.github/PULL_REQUEST_TEMPLATE.md

@@ -27,8 +27,8 @@
 <!-- Include sample dive log or other relevant information to allow testing the change where feasible. -->
 
 ### Release note:
-<!-- Describe if this change needs a release note present in ReleaseNotes/ReleaseNotes.txt. -->
-<!-- Also, please make sure to update the ReleaseNotes/ReleaseNotes.txt file itself. -->
+<!-- Describe if this change needs a release note present in CHANGELOG.md. -->
+<!-- Also, please make sure to add the release note on top of the file CHANGELOG.md. -->
 
 ### Documentation change:
 <!-- If this PR makes changes to user functionality, then the documentation has to be updated too. -->

CHANGELOG.md

@@ -0,0 +1,18 @@
+- Limit min. GFlow to 10 and min. GFhigh to 40 in preferences for profile
+  and planner
+- Fix issues related to debug logging on Windows
+- Add "Bluetooth mode" in the BT selection dialog: Auto, LE, Classical
+- Correct display of cylinder pressures for merged dives
+- Allow user defined cylinders as default in preferences (#821)
+- mobile: fix black/white switch in splash screen (#531)
+- UI: tag editing. Comma entry shows all tags (again) (#605)
+- mobile: enable auto completion for dive site entry (#546)
+- Printing: the bundled templates are now read-only and are always overwritten
+  by the application. The first time the user runs this update, backup files
+  of the previous templates would be created (#847)
+- Fix issues with filters not updating after changes to the dive list
+  (#551, #675)
+- map-widget: allow updating coordinates on the map when the user
+  is editing a dive site by pressing Enter or clicking a "flag" button
+- map-widget: prevent glitches when the user is interacting with the map
+  while animations are in progress

ReleaseNotes/ReleaseNotes.txt

@@ -1,31 +1,10 @@
+Please add release notes on top of the file /CHANGELOG.md
+
 // _Subsurface_ 4.7.5 Release Notes
 
 _Subsurface_ 4.7.5 - Month dd, 2017
 ------------------------------------------
 
-Some of the changes since _Subsurface_ 4.7.4
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-- Limit min. GFlow to 10 and min. GFhigh to 40 in preferences for profile
-  and planner
-- Fix issues related to debug logging on Windows
-- Add "Bluetooth mode" in the BT selection dialog: Auto, LE, Classical
-- Correct display of cylinder pressures for merged dives
-- Allow user defined cylinders as default in preferences (#821)
-- mobile: fix black/white switch in splash screen (#531)
-- UI: tag editing. Comma entry shows all tags (again) (#605)
-- mobile: enable auto completion for dive site entry (#546)
-- Printing: the bundled templates are now read-only and are always overwritten
-  by the application. The first time the user runs this update, backup files
-  of the previous templates would be created (#847)
-- Fix issues with filters not updating after changes to the dive list
-  (#551, #675)
-- map-widget: allow updating coordinates on the map when the user
-  is editing a dive site by pressing Enter or clicking a "flag" button
-- map-widget: prevent glitches when the user is interacting with the map
-  while animations are in progress
-
-
 Some of the changes since _Subsurface_ 4.7.2
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~