Updates for Go 1.18

Bump module version to Go 1.17.

Remove all +build directives now that the minimum supported Go version
understands //go:build.

Run 'go mod tidy' to include all indirect requirements in the go.mod
file.

Remove references to older Go versions in the README.

Update build matrix to test with 1.18, and remove 1.16.

.github/workflows/go.yml

@@ -6,7 +6,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go: [1.16, 1.17]
+        go: [1.17, 1.18]
     steps:
       - name: Set up Go
         uses: actions/setup-go@v2

README.md

@@ -74,7 +74,7 @@ https://decred.org/downloads/
 
 ### Build from source (all platforms)
 
-- **Install Go 1.15 or 1.16**
+- **Install Go 1.17 or 1.18**
 
   Installation instructions can be found here: https://golang.org/doc/install.
   Ensure Go was installed properly and is a supported version:
@@ -88,8 +88,7 @@ https://decred.org/downloads/
 - **Build or Update dcrwallet**
 
   Since dcrwallet is a single Go module, it's possible to use a single command
-  to download, build, and install without needing to clone the repo. If using Go
-  1.16, run
+  to download, build, and install without needing to clone the repo. Run:
 
   ```sh
   $ go install decred.org/dcrwallet/v2@master

go.mod

@@ -1,6 +1,6 @@
 module decred.org/dcrwallet/v2
 
-go 1.16
+go 1.17
 
 require (
 	decred.org/cspp/v2 v2.0.0
@@ -39,3 +39,16 @@ require (
 	google.golang.org/grpc v1.32.0
 	google.golang.org/protobuf v1.23.0
 )
+
+require (
+	github.com/agl/ed25519 v0.0.0-20170116200512-5312a6153412 // indirect
+	github.com/companyzero/sntrup4591761 v0.0.0-20200131011700-2b0d299dbd22 // indirect
+	github.com/dchest/siphash v1.2.2 // indirect
+	github.com/decred/base58 v1.0.3 // indirect
+	github.com/decred/dcrd/database/v3 v3.0.0 // indirect
+	github.com/decred/dcrd/dcrec/edwards/v2 v2.0.2 // indirect
+	golang.org/x/net v0.0.0-20210226172049-e18ecbb05110 // indirect
+	golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1 // indirect
+	golang.org/x/text v0.3.3 // indirect
+	google.golang.org/genproto v0.0.0-20190819201941-24fa4b261c55 // indirect
+)

internal/rpchelp/genrpcserverhelp.go

@@ -4,7 +4,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build generate
-// +build generate
 
 package main
 

internal/rpchelp/helpdescs_en_US.go

@@ -4,7 +4,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !generate
-// +build !generate
 
 package rpchelp
 

internal/rpchelp/methods.go

@@ -4,7 +4,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !generate
-// +build !generate
 
 package rpchelp
 

signal_unix.go

@@ -4,7 +4,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
-// +build darwin dragonfly freebsd linux netbsd openbsd solaris
 
 package main
 

version/version_buildinfo.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build go1.18
-// +build go1.18
 
 package version
 

version/version_nobuildinfo.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build !go1.18
-// +build !go1.18
 
 package version
 

wallet/udb/txexample_test.go

@@ -4,7 +4,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build ignore
-// +build ignore
 
 package udb
 

wallet/udb/txquery_test.go

@@ -4,7 +4,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build ignore
-// +build ignore
 
 package udb
 

wallet/walletdb/example_test.go

@@ -5,7 +5,6 @@
 
 // Test must be updated for API changes.
 //go:build disabled
-// +build disabled
 
 package walletdb_test