merge libmaple docs ("leaflabs-docs") into ./docs

In the past, libample documentation was forked out of this repository
because the documentation had increased in scope. For the librambutan,
and the rambutan project in general, we will try to keep documentation
closer to the source code, so the librambutan-specific documentation
should live here. Other sections of leaflabs-docs will be culled in a
following commit.

This merge attempts to maintain history by using a subtree strategy.
Followed directions at:

    http://nuclearsquid.com/writings/subtree-merging-and-you/

Full history for files should be accessible using the "--follow" flag to
git log, eg:

    git log --follow docs/source/adc.rst

It should be possible to pull patches from leaflabs-docs with:

    git pull -s subtree leaflabs-docs master

... at least until the docs in this repository diverge significantly.

1 files changed, 62 insertions, 0 deletions

diff --git a/docs/source/lang/api/delaymicroseconds.rst b/docs/source/lang/api/delaymicroseconds.rst
new file mode 100644
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+.. highlight:: cpp
+
+.. _lang-delaymicroseconds:
+
+delayMicroseconds()
+===================
+
+Pauses the program for the amount of time (in microseconds)
+specified as parameter. There are a thousand microseconds in a
+millisecond, and a million microseconds in a second.
+
+Library Documentation
+---------------------
+
+.. doxygenfunction:: delayMicroseconds
+
+
+Example
+-------
+
+The following example configures pin number 8 to work as an output
+pin, and sends a train of pulses with a period of roughly 100
+microseconds::
+
+    int outPin = 8;
+
+    void setup() {
+      pinMode(outPin, OUTPUT);      // sets the digital pin as output
+    }
+
+    void loop() {
+      digitalWrite(outPin, HIGH);   // sets the pin on
+      delayMicroseconds(50);        // pauses for 50 microseconds
+      digitalWrite(outPin, LOW);    // sets the pin off
+      delayMicroseconds(50);        // pauses for 50 microseconds
+    }
+
+
+Caveats and Known Issues
+------------------------
+
+The longest time ``delayMicroseconds()`` can delay is bounded by its
+argument type and the STM32 clock rate to be (2^32 - 1) / 12
+microseconds, or less than 6 minutes.  For longer pauses, use of
+:ref:`lang-delay` is possible.
+
+Arduino Compatibility
+---------------------
+
+While we have made every effort we could to ensure that the timing of
+``delayMicroseconds()`` is as accurate as possible, we cannot
+guarantee it will behave as the Arduino implementation down to the
+microsecond, especially for smaller values of ``us``.
+
+See Also
+--------
+
+-  :ref:`millis <lang-millis>`
+-  :ref:`micros <lang-micros>`
+-  :ref:`delay <lang-delay>`
+
+.. include:: /arduino-cc-attribution.txt