There are two issues fixed:
- With the latest Nim version sometimes the files
`<package_name>_<some_number>.nims`' generated on `nim install`
contain warning for unused imports which causes the test
"can validate package structure (#144)" to fail, because it was
searching for the word "warning" in the output.
- On Windows Subsystem for Linux, when an import starts sometimes with
a lowercase, and sometimes with an uppercase, for example
`import uri` and `import Uri`, this causes Nim to create and compile
both `stdlib_uri.nim.c` and `stdlib_Uri.nim.c` and to fail on the
linking step, because of the same symbols are being redefined.
Also the Travis CI build script is changed to test against currently the
latest working Nim version 212ae2f.
Related to #680
df11a6f6cf