Add lambda snippets

## Description
Add five flavours of lambda snippet for the C++11 snippet collection

## Results
Using the new snippets yields the following:
lamref:
```c++
[&](args) {
	/*code*/
}
```

lamval
```c++
[=](args) {
	/*code*/
}
```

lamret
```c++
[capture](args) -> return {
	/*code*/
}
```

lammin
```c++
[capture] {
	/*code*/
}
```

lamfull
```c++
[capture](args) mutable exception attribute -> return {
	/*code*/
}
```

They can all be readily plugged in to functions like std::for_each et. al.