Rewrite the PIC image format handler

It now uses QDataStream to deal with endianness. It also supports
several QImageIOHandler options.

This comes with a more comprehensive test suite than the old code. Note
that the old test suite was incorrect as the old code wrote the floats
in the header out incorrectly (although no-one noticed because no
software seems to care about those values).

All the test PIC files in the test suite appear correct according to the
specification (by inspection with Okteta). Unfortunately, there is a
lack of other freely-available software that reads and writes PIC files
(the main application that uses them is proprietary), and so this is the
best I can do.

REVIEW: 117944

autotests/CMakeLists.txt

@@ -56,7 +56,6 @@ endmacro()
 # result against the data read from the corresponding png file
 kimageformats_read_tests(
     pcx
-    pic
     psd
     ras
     rgb
@@ -101,3 +100,16 @@ endif()
 if (OpenEXR_FOUND)
     # FIXME: OpenEXR tests
 endif()
+
+
+find_package(Qt5Test ${REQUIRED_QT_VERSION} CONFIG QUIET)
+
+if(NOT Qt5Test_FOUND)
+    message(STATUS "Qt5Test not found, some autotests will not be built.")
+    return()
+endif()
+
+add_executable(pictest pictest.cpp)
+target_link_libraries(pictest Qt5::Gui Qt5::Test)
+ecm_mark_as_test(pictest)
+add_test(NAME kimageformats-pic COMMAND pictest)