Soft-Test-Failures

Multiple test failures, any one of which will result in a failed test. Like gtest's EXPECT_* rather than ASSERT_*.

```rust

[test]

fn expectfailures() { let x = 4; let y = "is not"; let z = 5; expect!(2 + 2 == 5, "{} surely {} {}", x, y, z); expect!(1 + 1 == 2); expect!(3 - 7 == -4); expect!(3 - 7 == -3); letfail!(); }

```

```txt running 1 test test expect_failures ... FAILED

failures:

---- expectfailures stdout ---- thread 'expectfailures' panicked at 'expect test failed with 2 failed assertions: 1: 4 surely is not 5 2: Expected 3 - 7 == -3 ', src/lib.rs:48:5 note: Run with RUST_BACKTRACE=1 for a backtrace.

```