Implement support for XZ dist tarball

Motivation
----------
Currenly tarballs for linux created manually. ZIP files are not
suitable, because they do not preserve unix file permissions.

Modification
------------
Implement 'koch xz' command to produce dist tarball in xz format. Also
the same command implemented in niminst.nim.

Result
------
Now it is easy to create source distribution for git stapshot and use it
further in packaging scripts.

tools/niminst/niminst.nim

@@ -36,6 +36,7 @@ type
     actionScripts # action: create install and deinstall scripts
     actionZip,    # action: create zip file
     actionTargz,  # action: create targz file
+    actionXz,     # action: create xz file
     actionDeb     # action: prepare deb package
 
   FileCategory = enum
@@ -173,6 +174,7 @@ proc parseCmdLine(c: var ConfigData) =
           of "scripts": incl(c.actions, actionScripts)
           of "zip": incl(c.actions, actionZip)
           of "targz": incl(c.actions, actionTargz)
+          of "xz": incl(c.actions, actionXz)
           of "inno": incl(c.actions, actionInno)
           of "nsis": incl(c.actions, actionNsis)
           of "deb": incl(c.actions, actionDeb)
@@ -600,6 +602,44 @@ proc targzDist(c: var ConfigData) =
   finally:
     setCurrentDir(oldDir)
 
+proc xzDist(c: var ConfigData) =
+  let proj = toLower(c.name) & "-" & c.version
+  var n = "$#.tar.xz" % proj
+  let tmpDir = if c.outdir.len == 0: "build" else: c.outdir
+
+  template processFile(z, dest, src) =
+    let s = src
+    let d = dest
+    echo "Copying ", s, " to ", tmpDir / d
+    let destdir = tmpdir / d.splitFile.dir
+    if not dirExists(destdir): createDir(destdir)
+    copyFile(s, tmpDir / d)
+
+  processFile(z, proj / buildBatFile32, "build" / buildBatFile32)
+  processFile(z, proj / buildBatFile64, "build" / buildBatFile64)
+  processFile(z, proj / buildShFile, "build" / buildShFile)
+  processFile(z, proj / makeFile, "build" / makeFile)
+  processFile(z, proj / installShFile, installShFile)
+  processFile(z, proj / deinstallShFile, deinstallShFile)
+  for f in walkFiles(c.libpath / "lib/*.h"):
+    processFile(z, proj / "c_code" / extractFilename(f), f)
+  for osA in 1..c.oses.len:
+    for cpuA in 1..c.cpus.len:
+      var dir = buildDir(osA, cpuA)
+      for k, f in walkDir("build" / dir):
+        if k == pcFile: processFile(z, proj / dir / extractFilename(f), f)
+
+  for cat in items({fcConfig..fcOther, fcUnix}):
+    for f in items(c.cat[cat]): processFile(z, proj / f, f)
+
+  let oldDir = getCurrentDir()
+  setCurrentDir(tmpDir)
+  try:
+    if execShellCmd("tar Jcf $1.tar.xz $1" % proj) != 0:
+      echo("External program failed")
+  finally:
+    setCurrentDir(oldDir)
+
 # -- prepare build files for .deb creation
 
 proc debDist(c: var ConfigData) =
@@ -668,5 +708,7 @@ if actionZip in c.actions:
     quit("libzip is not installed")
 if actionTargz in c.actions:
   targzDist(c)
+if actionXz in c.actions:
+  xzDist(c)
 if actionDeb in c.actions:
   debDist(c)