Add CI build status

Skip unused source files

continuous integration: Add arm_cortexM4l_math library to linker

Continuous Integration

Hi @PaulStoffregen,

I see that your project contains the practical examples. All of us understand that it’s not easy to test them before each new commit to this repository. What is more, need to be sure that all of these examples are actual and compile without errors.

I propose to solve this task using [Continuous integration](https://en.wikipedia.org/wiki/Continuous_integration) practice which is intended to detect [integration bugs](https://en.wikipedia.org/wiki/Software_testing#Integration_testing) and save time over the lifespan of a project.

## How does it work?
The each new commit to this repository will be tested using existing examples with appropriate platforms/embedded boards. @PlatformIO is used here as cross-platform code builder and library manager in pair with @travis-ci (distributed continuous integration service). 

## Quickstart
Please enable @travis-ci following the steps 1, 2 and 5 here http://docs.travis-ci.com/user/getting-started/#To-get-started-with-Travis-CI%3A 

For more details please follow to:

* Official Travis CI Documentation for PlatformIO: https://docs.travis-ci.com/user/integration/platformio/
* PlatformIO documentation for Travis CI: http://docs.platformio.org/en/latest/ci/travis.html

## Status Badge
You can add [badge with build status](https://docs.travis-ci.com/user/status-images/) to your README

**Markdown**
```
[![Build Status](https://travis-ci.org/PaulStoffregen/Audio.svg?branch=master)](https://travis-ci.org/PaulStoffregen/Audio)
```

**RST**
```
.. image:: https://travis-ci.org/PaulStoffregen/Audio.svg?branch=master
    :target: https://travis-ci.org/PaulStoffregen/Audio
```

## Examples

* Project [USB_Host_Shield_2.0](https://github.com/felis/USB_Host_Shield_2.0) [![Build Status](https://travis-ci.org/felis/USB_Host_Shield_2.0.svg?branch=master)](https://travis-ci.org/felis/USB_Host_Shield_2.0)
* Project [Arduino-IRremote](https://github.com/z3t0/Arduino-IRremote) [![Build Status](https://travis-ci.org/z3t0/Arduino-IRremote.svg?branch=master)](https://travis-ci.org/z3t0/Arduino-IRremote)
* Project [ethercard](https://github.com/jcw/ethercard) [![Build Status](https://travis-ci.org/jcw/ethercard.svg?branch=master)](https://travis-ci.org/jcw/ethercard)

Handle all nested examples

More examples for http://platformio.org/#!/lib/show/70/Audio

Again import improvements

Add dependent SerialFlash library

Improvement: import ignores lines which start with an known type but ends not with an ";"
Tidy up: deleted the "resources" folder, all static data is in the index.html file
Prepared: Looking for a solution to semi-automatic arrange imported nodes without coordinates

Exclude extras folder and specify version

Improvement: import is now very error tolerant

Bugfix: import function - undefined variable

Bugfix: added the loading of the static form data

Some bugfixes and some improvements

Removed the extern files, except the JSON file with the node descriptions, this will be loaded in offline mode too.

- fixed: clear selected nodes, works with several or all selected nodes (reason: two counting variables with the same name "i" where used in two nested loops)
- new: change node names (you can assign names to the nodes, these will be used as IDs if exported or re-imported to CPP (Arduino code)
- fixed: import merges imported nodes to existings ones, skipping nodes with the same name
- fixed: tooltips are now working, extracting the first paragraph of the HTML code
- new: nodes definition extracted to JSON file
- new: nodes help pages extracted to single HTML files
- new: form pages extracted to single HTML files
- new: asynchronous loading of JSON, help and form data, data will only be loaded when needed
- style: adapted the size of the palette, labels had been partially hidden

Import function for code from Arduino IDE

Small correction

corrected image link pathes

https://forum.pjrc.com/threads/31351-Teensyduino-1-26-Beta-3-Available?p=87620&viewfull=1#post87620