Fixed Doxygen comments for LinearDigitalFilter (#198)

wpilibc/shared/include/Filters/LinearDigitalFilter.h

@@ -18,17 +18,17 @@
  * filters are supported. Static factory methods are provided to create commonly
  * used types of filters.
  *
- * Filters are of the form:
- *  y[n] = (b0*x[n] + b1*x[n-1] + ... + bP*x[n-P]) - (a0*y[n-1] + a2*y[n-2] +
- * ... + aQ*y[n-Q])
+ * Filters are of the form:<br>
+ *  y[n] = (b0 * x[n] + b1 * x[n-1] + … + bP * x[n-P]) -
+ *         (a0 * y[n-1] + a2 * y[n-2] + … + aQ * y[n-Q])
  *
- * Where:
- *  y[n] is the output at time "n"
- *  x[n] is the input at time "n"
- *  y[n-1] is the output from the LAST time step ("n-1")
- *  x[n-1] is the input from the LAST time step ("n-1")
- *  b0...bP are the "feedforward" (FIR) gains
- *  a0...aQ are the "feedback" (IIR) gains
+ * Where:<br>
+ *  y[n] is the output at time "n"<br>
+ *  x[n] is the input at time "n"<br>
+ *  y[n-1] is the output from the LAST time step ("n-1")<br>
+ *  x[n-1] is the input from the LAST time step ("n-1")<br>
+ *  b0 … bP are the "feedforward" (FIR) gains<br>
+ *  a0 … aQ are the "feedback" (IIR) gains<br>
  * IMPORTANT! Note the "-" sign in front of the feedback term! This is a common
  *            convention in signal processing.
  *
@@ -48,10 +48,10 @@
  *    electrical or mechanical components
  *  - If you use clever gains, you can make a PID controller out of this class!
  *
- * For more on filters, I highly recommend the following articles:
- *  http://en.wikipedia.org/wiki/Linear_filter
- *  http://en.wikipedia.org/wiki/Iir_filter
- *  http://en.wikipedia.org/wiki/Fir_filter
+ * For more on filters, I highly recommend the following articles:<br>
+ *  http://en.wikipedia.org/wiki/Linear_filter<br>
+ *  http://en.wikipedia.org/wiki/Iir_filter<br>
+ *  http://en.wikipedia.org/wiki/Fir_filter<br>
  *
  * Note 1: PIDGet() should be called by the user on a known, regular period.
  * You can set up a Notifier to do this (look at the WPILib PIDController