Move all book-related images under "img"

Also:
 * use the "absolute path" syntax as used in the rest
of the image locations
 * png files are no longer required since we use svg for
   the web version and convert to PDF for the PDF version

Author: dietmarw

text/Makefile

@@ -10,7 +10,7 @@ BUILDDIR      = build
 # Variables for the SVG2PDF generation
 SOURCEDIR     = source
 #IMAGEDIRS can be a list of directories that contain SVG files and are relative to the SOURCEDIR
-IMAGEDIRS      = docs-dir/Icons $(shell find $(SOURCEDIR)/ModelicaByExample/ -name "*.svg" -exec dirname {} ";" | sort -u)
+IMAGEDIRS      = docs-dir/Icons source/_static/img $(shell find $(SOURCEDIR)/ModelicaByExample/ -name "*.svg" -exec dirname {} ";" | sort -u)
 
 # SVG to PDF conversion
 SVG2PDF       = rsvg-convert

text/source/_static/Aaron.jpg renamed to text/source/_static/img/Aaron.jpg

@@ -14,7 +14,7 @@ behavior involving arrays.
 Our problems will center around the a simple heat transfer problem.
 Consider a one-dimensional rod like the one shown below:
 
-.. image:: /_static/images/bar.*
+.. image:: /_static/img/bar.*
    :width: 50%
    :align: center
    :alt: Discretization of a one-dimensional bar
@@ -154,7 +154,7 @@ following declarations:
    :lines: 25-26
 
 Finally, the only array in this problem is the temperature of each
-section (since this is the only quantity that actually varies along the length of 
+section (since this is the only quantity that actually varies along the length of
 the rod):
 
 .. literalinclude:: /ModelicaByExample/ArrayEquations/HeatTransfer/Rod_ForLoop.mo

text/source/_static/img/RLC_low-pass.png

@@ -8,7 +8,7 @@ familiar with electrical systems, consider the following circuit:
 
 .. _low-pass-rlc:
 
-.. figure:: ../../_static/img/RLC_low-pass.png
+.. figure:: /_static/img/RLC_low-pass.*
     :align: center
     :width: 50%
     :alt: Low-Pass RLC Filter

text/source/_static/img/RLC_parallel_circuit_v1.png

@@ -12,7 +12,7 @@ Dedication
 
 .. only:: not latex
 
-  .. image:: ../_static/Aaron.jpg
+  .. image:: /_static/img/Aaron.jpg
      :align: right
 
 This book started as a Kickstarter project.  The idea of writing a