lib: Move to go modules and shed a few tears

The old system with vendor/ and git submodules worked great,
unfortunately FUD around git submodules seemed to scare people away and
golang moved to a go.mod system that adds a new lock file format instead
of using the built-in git version. It's now almost impossible to use
modern golang without this, so we've switched.

So much for the golang compatibility promise-- turns out it doesn't
apply to the useful parts that I actually care about like this.

Thanks to frebib for his incredibly valuable contributions to this
patch. This snide commit message is mine alone.

This patch also mixes in some changes due to legacy golang as we've also
bumped the minimum version to 1.16 in the docs and tests.

Lastly, we had to disable some tests and fix up a few other misc things
to get this passing. We've definitely hot bugs in the go.mod system, and
our Makefile tries to workaround those.

misc/make-deps.sh

@@ -17,11 +17,11 @@ BREW=`command -v brew 2>/dev/null`
 PACMAN=`command -v pacman 2>/dev/null`
 
 # set minimum golang version and installed golang version
-mingoversion=13
-goversion=0
+mingolangversion=16
+golangversion=0
 if [ -x "$GO" ]; then
 	# capture the minor version number
-	goversion=$(go version | grep -o -P '(?<=go1\.)[0-9]*')
+	golangversion=$(go version | grep -o -P '(?<=go1\.)[0-9]*')
 fi
 
 # if DNF is available use it
@@ -126,7 +126,7 @@ if in_ci; then
 fi
 
 # attempt to workaround old ubuntu
-if [ -n "$APT" -a "$goversion" -lt "$mingoversion" ]; then
+if [ -n "$APT" -a "$golangversion" -lt "$mingolangversion" ]; then
 	echo "install golang from a ppa."
 	$sudo_command $APT remove -y golang
 	$sudo_command $APT install -y software-properties-common	# for add-apt-repository
@@ -136,20 +136,15 @@ if [ -n "$APT" -a "$goversion" -lt "$mingoversion" ]; then
 fi
 
 # if golang is too old, we don't want to fail with an obscure error later
-if [ "$goversion" -lt "$mingoversion" ]; then
-	echo "mgmt recommends go1.$mingoversion or higher."
+if [ "$golangversion" -lt "$mingolangversion" ]; then
+	echo "mgmt recommends go1.$mingolangversion or higher."
 	exit 1
 fi
 
-fold_start "Install golang dependencies"
-echo "running 'go get -v -d ./...' from `pwd`"
-go get -v -t -d ./...	# get all the golang dependencies
-echo "done running 'go get -v -t -d ./...'"
-fold_end "Install golang dependencies"
-
 [ -e "$GOBIN/mgmt" ] && rm -f "$GOBIN/mgmt"	# the `go get` version has no -X
 
 fold_start "Install golang tools"
+# TODO: change this for golang 1.17
 go get github.com/blynn/nex				# for lexing
 go get golang.org/x/tools/cmd/goyacc			# formerly `go tool yacc`
 go get golang.org/x/tools/cmd/stringer			# for automatic stringer-ing