Remove references to "master" (#118)

Author: theofidry

README.md

@@ -7,7 +7,7 @@ How it works
 ------------
 
 When you launch a command with multiprocessing enabled (`--processes 2`), a
-master process fetches *items* and distributes them across the given number of
+main process fetches *items* and distributes them across the given number of
 child processes. Child processes are killed after a fixed number of items
 (a *segment*) in order to prevent them from slowing down over time.
 
@@ -101,18 +101,18 @@ Processed 2768 movies.
 Items
 -----
 
-The master process fetches all the items that need to be processed and passes
+The main process fetches all the items that need to be processed and passes
 them to the child processes through their Standard Input. Hence, items must
 fulfill two requirements:
 
 * Items must be strings
 * Items must not contain newlines
 
 Typically, you want to keep items small in order to offload processing from the
-master process to the child process. Some typical examples for items:
+main process to the child process. Some typical examples for items:
 
-* The master process reads a file and passes the lines to the child processes
-* The master processes fetches IDs of database rows that need to be updated and passes them to the child processes
+* The main process reads a file and passes the lines to the child processes
+* The main processes fetches IDs of database rows that need to be updated and passes them to the child processes
 
 Segments
 --------

src/ParallelExecutor.php

@@ -278,7 +278,7 @@ private function executeMainProcess(
     /**
      * Executes the child process.
      *
-     * This method reads the items from the standard input that the master process
+     * This method reads the items from the standard input that the main process
      * piped into the process. These items are passed to runSingleCommand() one
      * by one.
      */
@@ -414,7 +414,7 @@ private function createChildCommand(InputInterface $input): array
     }
 
     /**
-     * Called whenever data is received in the master process from a child process.
+     * Called whenever data is received in the main process from a child process.
      *
      * @param string $buffer The received data
      */

src/Parallelization.php

@@ -80,7 +80,7 @@ protected static function configureParallelization(Command $command): void
      * Typically, you will fetch all the items of the database objects that
      * you want to process here. These will be passed to runSingleCommand().
      *
-     * This method is called exactly once in the master process.
+     * This method is called exactly once in the main process.
      *
      * @param InputInterface $input The console input
      *