Documentation update

Rework for Doxygen >1.8. Moved large parts of the documentation to a
simplified format, making use of Markdown enhancements and fixing bad
long options.

doc_src/block.txt

@@ -1,40 +1,44 @@
 \section block block - temporarily block delivery of events
 
 \subsection block-synopsis Synopsis
- <tt>block [OPTIONS...]</tt>
+\fish{syn}
+block [OPTIONS...]
+\endfish
 
 \subsection block-description Description
 
-\c block prevents events triggered by \c fish or the
-<a href="commands.html#emit"><code>emit</code></a> command from
+`block` prevents events triggered by `fish` or the
+<a href="commands.html#emit">`emit`</a> command from
 being delivered and acted upon while the block is in place.
 
-In functions, \c block can be useful while performing work that
+In functions, `block` can be useful while performing work that
 should not be interrupted by the shell.
 
 The block can be removed. Any events which triggered while the
 block was in place will then be delivered.
 
 Event blocks should not be confused with code blocks, which are created
-with <code>begin</code>, <code>if</code>, <code>while</code> or
-<code>for</code>
+with `begin`, `if`, `while` or
+`for`
 
 The following parameters are available:
 
-- <tt>-l</tt> or <tt>--local</tt> Release the block automatically at the end of the current innermost code block scope
-- <tt>-g</tt> or <tt>--global</tt> Never automatically release the lock
-- <tt>-e</tt> or <tt>--erase</tt> Release global block
+- `-l` or `--local` Release the block automatically at the end of the current innermost code block scope
+- `-g` or `--global` Never automatically release the lock
+- `-e` or `--erase` Release global block
 
 \subsection block-example Example
 
-<pre>
+\fish
 # Create a function that listens for events
 function --on-event foo foo; echo 'foo fired'; end
+
 # Block the delivery of events
 block -g
+
 emit foo
 # No output will be produced
+
 block -e
 # 'foo fired' will now be printed
-</pre>
-
+\endfish