Fix multiple quality issues in the source

This PR fixes multiple issues in the source code to address issues raised by
tests/scripts/check-files.py. Specifically:
 * incorrect file permissions
 * missing newline at the end of files
 * trailing whitespace
 * Tabs present
 * TODOs in the souce code
diff --git a/library/net.c b/library/net.c
index e8123cc..2898128 100644
--- a/library/net.c
+++ b/library/net.c
@@ -261,7 +261,7 @@
 static int net_would_block( const mbedtls_net_context *ctx )
 {
     int err = errno;
-    
+
     /*
      * Never return 'WOULD BLOCK' on a non-blocking socket
      */