support subcommands on windows. Fixes #142
allow cflag style option params, unit test, fixes #174
improve unit test for #174
Merge pull request #176 from tonylukasavage/174-1

Support for `--cflags` style option parameters, unit test, fixes #174
Release 2.1.0
clean up usage argument summary

instead of using implicit array string conversion which includes confusing
commas, use an explicit .join(' ')
Merge pull request #173 from yiminghe/issue_142

support subcommands on windows. Fixes #142
Fixed failing test.
Pass previous option value or default value to coercion function so it can be used to collect values.
Merge pull request #198 from AlphaHydrae/repeated-options

Repeated options
refactor ternary
Release 2.2.0
Update Readme.md

Missing `collect`
if args is falsy, assume a default collection.

This is kind of an edge case.
When the command's option is not required, and the option is not optional, and we follow the

```
 *      program
 *        .command(..)
 *        .description(..)
 *        .action(function(){
 *        });
```

pattern, then after some event chaining args happens to be `undefined` which breaks the flow.

Providing a default value if args do not exist, will make the function less error-prone nonetheless; and it won't cause any regression in the existing behavior.
Added alias feature
Update main help too
Restore node versions in travis file
use SVG to display Travis CI build testing status
Merge pull request #214 from Mithgol/patch-1

use SVG to display Travis CI build testing status
Merge pull request #203 from plievone/patch-1

Update Readme.md