Upgrade pest crate

[wahn]

The pest crate reached now version 1.0 (or later):
https://github.com/pest-parser/pest
This needs some re-writing of the current code in examples/pest_test.rs.

[wahn]

I just created a new branch for this issue.

[wahn]

Since commit 53e75ca the Cornell Box scene renders fine:

[wahn]

Since commit ab4dbeb the Cafe Scene renders fine:

[wahn]

Since commit 4181179 the Art Gallery renders fine:

[wahn]

Since commit ad62f78 the Japanese Classroom renders fine:

[wahn]

Since commit 9dce61d the simple test scene for motion blur renders fine:

[wahn]

Merging and deleting the branch for this issue (see commit 211bc70). It's resolved now. Closing.