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/frc971/wpilib/loop_output_handler_test.cc b/frc971/wpilib/loop_output_handler_test.cc
index 0701bf5..b3fbb0d 100644
--- a/frc971/wpilib/loop_output_handler_test.cc
+++ b/frc971/wpilib/loop_output_handler_test.cc
@@ -107,8 +107,8 @@
 
   // Kick off the ping timer handler.
   test_event_loop_->OnRun([this, &timer_handle]() {
-    timer_handle->Setup(test_event_loop_->monotonic_now(),
-                        chrono::milliseconds(5));
+    timer_handle->Schedule(test_event_loop_->monotonic_now(),
+                           chrono::milliseconds(5));
   });
 
   event_loop_factory_.RunFor(chrono::seconds(2));