add sdkch to maintain PENDING.md effectively and free of file conflicts

Closes: #2380

.github/PULL_REQUEST_TEMPLATE.md

@@ -9,7 +9,7 @@ v    If a checkbox is n/a - please still include it but + a little note why
 - [ ] Linked to github-issue with discussion and accepted design OR link to spec that describes this work.
 - [ ] Wrote tests
 - [ ] Updated relevant documentation (`docs/`)
-- [ ] Added entries in `PENDING.md` with issue # 
+- [ ] Added a relevant changelog entry: `sdkch add [section] [stanza] [message]`
 - [ ] rereviewed `Files changed` in the github PR explorer
 
 ______

.pending/bugfixes/sdk/3837-Fix-WithdrawValidatorCommission-to-properly-set-the-validator-s-remaining-commission

@@ -0,0 +1 @@
+#3837 Fix `WithdrawValidatorCommission` to properly set the validator's remaining commission.

.pending/features/sdk/3813-New-sdk-NewCoins-safe-constructor-to-replace-bare

@@ -0,0 +1 @@
+#3813 New sdk.NewCoins safe constructor to replace bare sdk.Coins{} declarations.

.pending/improvements/gaia/3808-gaiad-and-gaiacli-integration-tests-use-build-binaries

@@ -0,0 +1 @@
+#3808 `gaiad` and `gaiacli` integration tests use ./build/ binaries.

.pending/improvements/gaiacli/3841-Add-indent-to-J

@@ -0,0 +1 @@
+#3841 Add indent to JSON of `gaiacli keys [add|show|list]`

.pending/improvements/gaiacli/3859-Add-newline-to-echo-of-gaiacli-keys

@@ -0,0 +1 @@
+#3859 Add newline to echo of `gaiacli keys ...`

.pending/improvements/sdk/3801-baseapp-safety-improvements

@@ -0,0 +1 @@
+#3801 `baseapp` safety improvements

.pending/improvements/sdk/3820-Make-Coins-IsAllGT-more-robust-and-consistent

@@ -0,0 +1 @@
+#3820 Make Coins.IsAllGT() more robust and consistent.

.pending/improvements/sdk/3828-New-sdkch-tool-to-maintain-changelogs

@@ -0,0 +1 @@
+#3828 New sdkch tool to maintain changelogs

.pending/improvements/sdk/3864-Make-Coins-IsAllGTE-more-consistent

@@ -0,0 +1 @@
+#3864 Make Coins.IsAllGTE() more consistent.

Makefile

@@ -118,13 +118,16 @@ update_dev_tools:
 	go get -u github.com/tendermint/lint/golint
 
 devtools: devtools-stamp
-devtools-clean: tools-clean
 devtools-stamp: tools
 	@echo "--> Downloading linters (this may take awhile)"
 	$(GOPATH)/src/github.com/alecthomas/gometalinter/scripts/install.sh -b $(GOBIN)
 	go get github.com/tendermint/lint/golint
+	go install ./cmd/sdkch
 	touch $@
 
+devtools-clean: tools-clean
+	rm -f devtools-stamp
+
 vendor-deps: tools
 	@echo "--> Generating vendor directory via dep ensure"
 	@rm -rf .vendor-new

cmd/sdkch/README.md

@@ -0,0 +1,50 @@
+# sdkch
+Simple tool to maintain modular changelogs
+
+# Usage
+
+```
+$ sdkch -help
+usage: sdkch [-d directory] [-prune] command
+
+Maintain unreleased changelog entries in a modular fashion.
+
+Commands:
+    add section stanza [message]    Add an entry file.
+                                    If message is empty, start the editor to edit
+                                    the message.
+    generate [version]              Generate a changelog in Markdown format and print
+                                    it to STDOUT. version defaults to UNRELEASED.
+
+    Sections             Stanzas
+         ---                 ---
+    breaking                gaia
+    features             gaiacli
+improvements            gaiarest
+    bugfixes                 sdk
+                      tendermint
+
+Flags:
+  -d string
+    	entry files directory (default "/home/alessio/work/tendermint/src/github.com/cosmos/cosmos-sdk/.pending")
+  -prune
+    	prune old entries after changelog generation
+```
+
+## Add a new entry
+
+You can either drop a text file in the appropriate directory or use the `add` command:
+
+```bash
+$ sdkch add features gaiacli '#3452 New cool gaiacli command'
+```
+
+If no message is provided, a new entry file is opened in an editor is started
+
+## Generate the full changelog
+
+```bash
+$ sdkch generate v0.30.0
+```
+
+The `-prune` flag would remove the old entry files after the changelog is generated.