This is a Sublime Text 3 plugin that makes a numberred list.

Text-item-list.py

# The MIT License (MIT)
# Copyright (c) 2016 Leonid Edrenkin
#
# This is a Sublime Text 3 plugin that makes and unmakes a numberred list.

# You should select text lines and apply one of commands:
#   view.run_command('make_numberred_list')
#   view.run_command('unmake_numberred_list')

import sublime, sublime_plugin
import re

class MakeNumberredList(sublime_plugin.TextCommand):
  def run(self, edit):
    v = self.view
    regions = [ s for s in self.view.sel() if not s.empty() ]

    if len(regions) == 0:
      return

    for region in regions:
      region = v.full_line(region)
      new_lines = []

      lines = v.split_by_newlines(region)
      item_num = 1
      for i, line in enumerate(lines):
        s = v.substr(line)
        s = s.rstrip()
        if len(s) > 0:
          s = str(item_num) + ") " + s
          item_num += 1
        s += "\n"
        new_lines.append(s)

      p = region.begin()
      v.erase(edit, region)
      v.insert(edit, p, ''.join(new_lines))


class UnmakeNumberredList(sublime_plugin.TextCommand):
  def run(self, edit):
    v = self.view
    regions = [ s for s in self.view.sel() if not s.empty() ]

    if len(regions) == 0:
      return

    for region in regions:
      region = v.full_line(region)
      new_lines = []

      lines = v.split_by_newlines(region)
      for line in lines:
        s = v.substr(line)
        s = s.rstrip()
        m = re.match("^\d+\s*\)\s*(.*)", s)
        if m: s = m.group(1)
        s += "\n"
        new_lines.append(s)

      p = region.begin()
      v.erase(edit, region)
      v.insert(edit, p, ''.join(new_lines))