Rename timer `Setup` function to `Schedule`

This patch was motivated by my desire to fix a typo in the function
name. The noun "setup" is 1 word. The verb "set up" is 2 words. All
other member functions are verbs, so this one should be a verb too.
That means that the function should be called `SetUp`. During the
discussion that resulted from the rename, James Kuszmaul pointed out
that "setting up" a timer can be confusing. It implies that you can
only "set up" a timer once. But the intent is to let users set up
timers as many times as they like. So we decided on renaming the
function to `Schedule`. That conveys the purpose and intent better.

I took this opportunity to fix some other typos involving the verb
"set up".

Signed-off-by: Philipp Schrader <philipp.schrader@gmail.com>
Change-Id: I2f557d1f946960af82711f248820d5e2d385a5d3
diff --git a/aos/starter/mock_starter.cc b/aos/starter/mock_starter.cc
index 1e06758..9f9a2b5 100644
--- a/aos/starter/mock_starter.cc
+++ b/aos/starter/mock_starter.cc
@@ -59,7 +59,7 @@
   }
 
   event_loop_->OnRun([this, send_timer]() {
-    send_timer->Setup(event_loop_->monotonic_now(), std::chrono::seconds(1));
+    send_timer->Schedule(event_loop_->monotonic_now(), std::chrono::seconds(1));
 
     for (const aos::Application *application :
          *event_loop_->configuration()->applications()) {