If no paths are provided, read source from stdin. Fix #165.

CHANGELOG.md

 # 0.1.4
 
 * Don't mangle comma after function-typed initializing formal (#156).
 * Add `--dry-run` option to show files that need formatting (#67).
 * Try to avoid splitting in before index argument (#158, #160).
 * Support `await for` statements (#154).
 * Don't delete commas between enum values with doc comments (#171).
 * Put a space between nested unary `-` calls (#170).
 * Allow `-t` flag to preserve compability with old formatter (#166).
 * Support `--machine` flag for machine-readable output (#164).
+* If no paths are provided, read source from stdin (#165).
 
 # 0.1.3
 
 * Split different operators with the same precedence equally (#130).
 * No spaces for empty for loop clauses (#132).
 * Don't touch files whose contents did not change (#127).
 * Skip formatting files in hidden directories (#125).
 * Don't include trailing whitespace when preserving selection (#124).
 * Force constructor initialization lists to their own line if the parameter
   list is split across multiple lines (#151).
 * Allow splitting in index operator calls (#140).
 * Handle sync* and async* syntax (#151).
 * Indent the parameter list more if the body is a wrapped "=>" (#144).
 
 # 0.1.2
 
 * Move split conditional operators to the beginning of the next line.
 
 # 0.1.1
 
 * Support formatting enums (#120).
 * Handle Windows line endings in multiline strings (#126).
 * Increase nesting for conditional operators (#122).