Compile files when zgen save is called

It compiles *.zsh, *.sh and zcomdump*, as well as all files with zsh
shebang (`#!...zsh`).
In these paths:
- zgen source files
- plugin files
- zcompdump (if custom path or ~/.zcompdump*)

This also adds `zgen compile <path>` to the api.

Closes tarjoilija/zgen#92

_zgen

@@ -16,6 +16,7 @@
 local -a _zgen_commands
 _zgen_commands=(
     "clone:clone plugin from repository"
+    "compile:compile files the given path"
     "completions:deprecated, please use load instead"
     "list:print init.zsh"
     "load:clone and load plugin"

zgen.zsh

@@ -289,6 +289,23 @@ zgen-save() {
     -zginit "# }}}"
 
     zgen-apply
+
+    -zgpute "Compiling files ..."
+    zgen-compile $ZGEN_DIR
+    if [[ $ZGEN_DIR != $ZGEN_SOURCE ]]; then
+        zgen-compile $ZGEN_SOURCE
+    fi
+    if [[ -n $ZGEN_CUSTOM_COMPDUMP ]]; then
+        -zgen-compile $ZGEN_CUSTOM_COMPDUMP
+    else
+        set -o nullglob
+        for compdump in $HOME/.zcompdump*; do
+            if [ $compdump = *.zwc ]; then
+                continue
+            fi
+            -zgen-compile $compdump
+        done
+    fi
 }
 
 zgen-apply() {
@@ -311,6 +328,42 @@ zgen-apply() {
     -zgputs "$(-zgen-get-clone-dir "$ZGEN_OH_MY_ZSH_REPO" "$ZGEN_OH_MY_ZSH_BRANCH")"
 }
 
+-zgen-compile() {
+    local file=$1
+    [ ! $file.zwc -nt $file ] && zcompile $file
+}
+
+zgen-compile() {
+    local inp=$1
+    if [ -z $inp ]; then
+        -zgpute '`compile` requires one parameter:'
+        -zgpute '`zgen compile <location>`'
+    elif [ -f $inp ]; then
+        -zgen-compile $inp
+    else
+        set -o nullglob
+        for file in $inp/**/*
+        do
+            # only files and ignore compiled files
+            if [ ! -f $file ] || [[ $file = *.zwc ]]; then
+                continue
+
+            # Check for shebang if not:
+            # - *.zsh
+            # - *.sh
+            # - zcompdump*
+            elif [[ $file != *.zsh ]] && [[ $file != *.sh ]] && [[ $file != *zcompdump* ]]; then
+                read -r firstline < $file
+                if [[ ! $firstline =~ '^#!.*zsh' ]] 2>/dev/null; then
+                    continue
+                fi
+            fi
+
+            -zgen-compile $file
+        done
+    fi
+}
+
 zgen-load() {
     if [[ "$#" == 0 ]]; then
         -zgpute '`load` requires at least one parameter:'
@@ -465,7 +518,7 @@ zgen() {
     local cmd="${1}"
     if [[ -z "${cmd}" ]]; then
         -zgputs 'usage: `zgen [command | instruction] [options]`'
-        -zgputs "    commands: list, saved, reset, clone, update, selfupdate"
+        -zgputs "    commands: list, saved, reset, clone, update, selfupdate, compile"
         -zgputs "    instructions: load, oh-my-zsh, pmodule, prezto, save, apply"
         return 1
     fi