Add .gitattributes to .npmignore

One of the dependencies, hawk, uses CRLF line endings. If you use less
in your project and check in node_modules to source control, git sees
the .gitattributes that is packaged with less and obeys it for that
subdirectory. This gives you line ending conflicts with hawk.

.gitattributes is not relevant to the packaged module and should not be
included anyway.
Add interface for a file loader rather than an importer
Change node to use the file loader interface
start seperating browser load stylesheet and loadFile
Move parsing into loadStylesheet from loadFile
move browser to parse inside parser
seperate sheet and env
Simplify more of loadFile and make more of the env creation common between node and browser
move new parseEnv into parser
Align the callback param orders
Add import inline option. Fixes #1209
multi comments in selectors and other places
Fix modifyVars to use a per file cache so less is re-evaluated properly. Also add tests and \n in case of comment on the last line
1.4.1 so far changelog changes
Add silent option
Basic functionality and basic tests for import silent
import silent - handle selectors containing amp
import silent: add tests for extends
import silent to work with media queries and directives
support comments. Add failing test case for when mixin call does not have parent selectors