Better travis build.

Author: Yamakaky

.travis.yml

@@ -1,31 +1,34 @@
 sudo: false
 language: rust
+cache: cargo
 addons:
   apt:
     packages:
     - libcurl4-openssl-dev
     - libelf-dev
     - libdw-dev
+
 rust:
 - stable
 - beta
 - nightly
+
 before_script:
 - |
   pip install 'travis-cargo<0.2' --user &&
   export PATH=$HOME/.local/bin:$PATH
+
 script:
-- |
-  travis-cargo build &&
-  travis-cargo test &&
-  travis-cargo --only nightly doc
-deploy:
-  provider: script
-  script: travis-cargo --only nightly doc-upload
-  on:
-    branch: master
+- cargo build --verbose $FEATURES
+- cargo test --verbose $FEATURES
+
+after_success:
+- travis-cargo --only stable doc
+- travis-cargo --only stable doc-upload
+
 env:
   global:
-  - TRAVIS_CARGO_NIGHTLY_FEATURE=""
-  - secure: TODO
   - secure: 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
+  matrix:
+  - FEATURES=--features=backtrace
+  - FEATURES=--no-default-features