docs: Convert to markdown

Author: tlsa

README

@@ -0,0 +1,56 @@
+LibCSS -- a CSS parser and selection engine
+===========================================
+
+Overview
+--------
+
+LibCSS is a CSS parser and selection engine. It aims to parse the forward
+compatible CSS grammar.
+
+Requirements
+------------
+
+LibCSS requires the following tools:
+
+* A C99 capable C compiler
+* GNU make or compatible
+* Pkg-config
+* Perl (for the testcases)
+* Python3 (minimum 3.6, for generated selection code)
+
+LibCSS also requires the following libraries to be installed:
+
+* LibParserUtils
+* LibWapcaplet
+
+Compilation
+-----------
+
+If necessary, modify the toolchain settings in the Makefile.
+Invoke make:
+
+    make
+
+Regenerating generated selection source code
+--------------------------------------------
+
+To regenerate the selection sources (computed style data accesses),
+note this requires python3:
+
+    make select_generator
+
+Verification
+------------
+
+To verify that the parser is working, it is necessary to specify a
+different makefile target than that used for normal compilation, thus:
+
+    make test
+
+API documentation
+-----------------
+
+Currently, there is none. However, the code is well commented and the
+public API may be found in the "include" directory. The testcase sources
+may also be of use in working out how to use it.
+

README.md

@@ -0,0 +1,77 @@
+LibCSS API & ABI Changes
+========================
+
+This document explains how to upgrade clients to use new versions of LibCSS.
+
+
+LibCSS 0.2.0 --> LibCSS 0.3.0
+-----------------------------
+
+Both the API and ABI are changed.
+
+LibCSS no longer lets clients provide a memory allocator function.
+This change affects the following functions:
+
+| Header                        | Function                    |
+| ----------------------------- | --------------------------- |
+| `include/libcss/computed.h`   | css_computed_style_create() |
+| `include/libcss/select.h`     | css_select_ctx_create()     |
+| `include/libcss/stylesheet.h` | css_stylesheet_create()     |
+
+
+There are changes to selection handler callback table:
+
+*   node_classes
+    * LibCSS no longer frees the any array of classes passed to the
+      node_classes callback.  It does still unref the individual strings.
+      This means clients need not allocate a new array each call, but can
+      keep the array cached on the node.
+
+*   set_libcss_node_data
+    * New selection handler function used to store a private cache belonging
+      to libcss on document element nodes.  When the node is deleted or
+      modified, clients should call css_libcss_node_data_handler().
+
+*   get_libcss_node_data
+    * New selection handler function used to retrieve private cache belonging
+      to libcss from document element nodes.
+
+
+LibCSS 0.3.0 --> LibCSS 0.4.0
+-----------------------------
+
+The API is changed.
+
+Due to the change from CSS2 overflow to CSS3 overflow properties, the
+computed style access functions for overflow properties have changed.
+The overflow property is removed.  Added are overflow-x and overflow-y
+properties.  (The overflow shorthand property now sets overflow-x and
+overflow-y.)
+
+This change affects the following functions:
+
+| Change  | Header                      | Function                    |
+| ------- | --------------------------- | --------------------------- |
+| Removed | `include/libcss/computed.h` | `css_computed_overflow()`   |
+| Added   | `include/libcss/computed.h` | `css_computed_overflow_x()` |
+| Added   | `include/libcss/computed.h` | `css_computed_overflow_y()` |
+
+
+LibCSS 0.5.0 --> LibCSS 0.6.0
+-----------------------------
+
+The API is changed.
+
+The way that presentational hints are handled has changed to be more
+optimal.  Instead of calling the presentational hint callback once
+per property per node to get each hint, we now call the callback once
+per node to get all the hints that apply to it.
+
+There are changes to selection handler callback table:
+
+*   node_presentational_hint
+    * Rather than asking for any hint for the given node and property,
+      it now asks for an array of hints that should apply to the node.
+
+The css_hint structure has been changed to include the property which
+the hint applies to.