Change how plugins/actions work a bit

This includes both how they detect what the current
mode (install/uninstall/cleanup/etc) is, and also forces them to
register themselves with Dotify. The registration will be used for
running pre/post hooks.

src/actions/git.sh

@@ -0,0 +1,32 @@
+# Register git action
+dotify-register-action "git"
+
+# Git action.
+dotify-action-git() {
+  local mode="$1"
+  ! local valid_mode="$(command -v "dotify-action-git-do-${mode}")"
+
+  if [ -n "$valid_mode" ]; then
+    shift 1
+    dotify-action-git-do-${mode} $@
+  fi
+}
+
+dotify-action-git-do-install() {
+  echo "git install: $@"
+}
+
+dotify-action-git-do-uninstall() {
+  echo "git uninstall: $@"
+}
+
+dotify-action-git-do-cleanup() {
+  echo "git cleanup: $@"
+}
+
+dotify-action-git-post-run() {
+  if [ "$1" == "cleanup" ]; then
+    shift 1
+    dotify-action-link-do-cleanup $@
+  fi
+}

src/actions/link.sh

@@ -0,0 +1,32 @@
+# Register link action.
+dotify-register-action "link"
+
+# Link action.
+dotify-action-link() {
+  local mode="$1"
+  ! local valid_mode="$(command -v "dotify-action-link-do-${mode}")"
+
+  if [ -n "$valid_mode" ]; then
+    shift 1
+    dotify-action-link-do-${mode} $@
+  fi
+}
+
+dotify-action-link-do-install() {
+  echo "link install: $@"
+}
+
+dotify-action-link-do-uninstall() {
+  echo "link uninstall: $@"
+}
+
+dotify-action-link-do-cleanup() {
+  echo "link cleanup: $@"
+}
+
+dotify-action-link-post-run() {
+  if [ "$1" == "cleanup" ]; then
+    shift 1
+    dotify-action-link-do-cleanup $@
+  fi
+}