fix calloc() calls

* size_t nmemb (number of elements) first, then size_t size
* do not assume char is size 1 but use sizeof()
* allocate for char, not pointer to char (found by Michael McConville,
  fixes #261)

freebsd/FreeBSDProcess.c

@@ -86,7 +86,7 @@ ProcessPidColumn Process_pidColumns[] = {
 };
 
 FreeBSDProcess* FreeBSDProcess_new(Settings* settings) {
-   FreeBSDProcess* this = calloc(sizeof(FreeBSDProcess), 1);
+   FreeBSDProcess* this = calloc(1, sizeof(FreeBSDProcess));
    Object_setClass(this, Class(FreeBSDProcess));
    Process_init(&this->super, settings);
    return this;