word generator compile error

gistfile1.txt

mk270@cornford ~/Src/word_generator> cargo build
    Updating git repository `https://github.com/rust-lang/rand.git`
 Downloading unicode-segmentation v0.1.0
 Downloading regex v0.1.30
   Compiling rustc-serialize v0.3.14
   Compiling regex v0.1.30
   Compiling libc v0.1.6
   Compiling unicode-segmentation v0.1.0
   Compiling rand v0.3.8 (https://github.com/rust-lang/rand.git#93544850)
   Compiling word_generator v0.1.0 (file:///home/mk270/Src/word_generator)
src/main.rs:1:1: 1:25 error: unstable feature
src/main.rs:1 #![feature(collections)]
              ^~~~~~~~~~~~~~~~~~~~~~~~
note: this feature may not be used in the beta release channel
src/main.rs:2:1: 2:21 error: unstable feature
src/main.rs:2 #![feature(convert)]
              ^~~~~~~~~~~~~~~~~~~~
note: this feature may not be used in the beta release channel
error: aborting due to 2 previous errors
Could not compile `word_generator`.

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