new angle-scan processing features, update documentation, bugfixes

new functions:
- voigt_fwhm_lor
- rotate_hemi_scan
- import_tpi_scan
- draw_diffraction_cone

updated functions:
- interpolate_hemi_scan
- display_hemi_scan
- duplicate_hemi_scan

updated documentation:
- installation instructions
- readme

doc/Doxyfile

@@ -758,7 +758,8 @@ WARN_LOGFILE           =
 # spaces.
 # Note: If this tag is empty the current directory is searched.
 
-INPUT                  = ../pearl
+INPUT                  = ../pearl \
+                         src
 
 # This tag can be used to specify the character encoding of the source files
 # that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses
@@ -778,7 +779,8 @@ INPUT_ENCODING         = CP1252
 # *.md, *.mm, *.dox, *.py, *.f90, *.f, *.for, *.tcl, *.vhd, *.vhdl, *.ucf,
 # *.qsf, *.as and *.js.
 
-FILE_PATTERNS          = *.ipf
+FILE_PATTERNS          = *.ipf \
+                         *.dox
 
 # The RECURSIVE tag can be used to specify whether or not subdirectories should
 # be searched for input files as well.
@@ -863,7 +865,7 @@ IMAGE_PATH             =
 # code is scanned, but not when the output code is generated. If lines are added
 # or removed, the anchors will not be placed correctly.
 
-INPUT_FILTER           = "gawk -f doxygen-filter-ipf.awk"
+INPUT_FILTER           =
 
 # The FILTER_PATTERNS tag can be used to specify filters on a per file pattern
 # basis. Doxygen will compare the file name with each pattern and apply the
@@ -872,7 +874,7 @@ INPUT_FILTER           = "gawk -f doxygen-filter-ipf.awk"
 # filters are used. If the FILTER_PATTERNS tag is empty or if none of the
 # patterns match the file name, INPUT_FILTER is applied.
 
-FILTER_PATTERNS        = 
+FILTER_PATTERNS        = "*.ipf=\"gawk -f doxygen-filter-ipf.awk\""
 
 # If the FILTER_SOURCE_FILES tag is set to YES, the input filter (if set using
 # INPUT_FILTER) will also be used to filter the input files that are used for