Implement sourcemap generation
Remove unnecessary code, add files that were left behind
Fix line counting in the sourcemap output
Follow review, remove unnecessary :id field and an unused method
Merge branch 'master' into sourcemap

Conflicts:
	lib/sass/scss/parser.rb
Changes to the structure and style of the source map patch.
Fix some off-by-one bugs in column calculations.
JSON dumping tests added, json_value_of return type and whitespace character dumping fixed
Merge pull request #524 from crdev/sourcemap

JSON dumping tests added, return type and special character escaping fixed
Get rid of Sass::Util.char_size.

This was causing as many problems as it fixed, since it didn't address other
byte-indexed methods on 1.8 (e.g. String#[]). Avoiding byte indexing pervasively
would be more effort than it's worth.
Rename SourceMapping to SourceMap.
Use NEWLINE in ToCss#output.
Use "offset" consistently, rather than "column".
Improve the Source* inspect methods.
Make SourcePosition one-based.

This makes it match the rest of the line/offset tracking in Sass.
Move Source* out of sass/tree.
Properly handle nested paths in Source::Map.
Rebuild sourcemaps in the watch/update modes
Keep track of the filename of each source range.
Keep track of the filename of each source range.