Reorganizing the Qt project files. Will rename projects for shared library

 - Pull out gcc warnings into qhull-warn.pri
 - Pull out libqhull files into qhull-libsrc.pri
 - Document location of qh_QHpointer
 - Use CONFIG incremental instead of vc option
 - user_eg2 links with shared library (project will be added later after rename)

src/qhull-libsrc.pri

+# -------------------------------------------------
+# qhull-libsrc.pri -- Qt include project for libqhull sources and headers
+#   libqhull.pro, libqhullp.pro, and libqhulldll.pro are the same for SOURCES and HEADERS
+# -------------------------------------------------
+
+# Duplicated in libqhull/libqhull.pro for ease of use in QtCreator
+# qset.c requires -fno-script-aliasing for gcc 4.1 to 4.3
+*g++ {
+    COMPVER = $$system(gcc -v)
+    contains(COMPVER,4.1)|contains(COMPVER,4.2)|contains(COMPVER,4.3) {
+        QMAKE_CFLAGS += -fno-strict-aliasing # Avoid core dumps in qset.c with -O2
+    }
+}
+# Order object files by frequency of execution.  Small files at end.
+# Current directory is caller
+SOURCES += ../libqhull/rboxlib.c
+SOURCES += ../libqhull/user.c
+SOURCES += ../libqhull/global.c
+SOURCES += ../libqhull/stat.c
+SOURCES += ../libqhull/io.c
+SOURCES += ../libqhull/geom2.c
+SOURCES += ../libqhull/poly2.c
+SOURCES += ../libqhull/merge.c
+SOURCES += ../libqhull/libqhull.c
+SOURCES += ../libqhull/geom.c
+SOURCES += ../libqhull/poly.c
+SOURCES += ../libqhull/qset.c
+SOURCES += ../libqhull/mem.c
+SOURCES += ../libqhull/usermem.c
+SOURCES += ../libqhull/userprintf.c
+SOURCES += ../libqhull/random.c
+
+HEADERS += ../libqhull/geom.h
+HEADERS += ../libqhull/io.h
+HEADERS += ../libqhull/libqhull.h
+HEADERS += ../libqhull/mem.h
+HEADERS += ../libqhull/merge.h
+HEADERS += ../libqhull/poly.h
+HEADERS += ../libqhull/random.h
+# The file, libqhull/qhull.h, is for backwards compatibility.
+HEADERS += ../libqhull/qhull_a.h
+HEADERS += ../libqhull/qset.h
+HEADERS += ../libqhull/stat.h
+HEADERS += ../libqhull/user.h

src/qhull-warn.pri

+# -------------------------------------------------
+# qhull-warn.pri -- Qt project warnings for warn_on
+#   CONFIG += qhull_warn_all        # Qhull compiles with all warnings except for qhull_warn_shadow and qhull_warn_conversion
+#   CONFIG += qhull_warn_conversion # Warn in Qt and Qhull about conversion errors
+#   CONFIG += qhull_warn_error      # Turn warnings into errors
+#   CONFIG += qhull_warn_shadow     # Warn in Qt about shadowing of functions and fields
+# -------------------------------------------------
+
+# Uncomment to report warnings as errors
+#CONFIG += qhull_warn_error
+
+*g++{
+    qhull_warn_error{
+        QMAKE_CFLAGS_WARN_ON += -Werror
+        QMAKE_CXXFLAGS_WARN_ON += -Werror
+    }
+
+    QMAKE_CFLAGS_WARN_ON += -Wcast-qual -Wextra -Wshadow -Wwrite-strings
+
+    QMAKE_CXXFLAGS_WARN_ON += -Wcast-qual -Wextra -Wwrite-strings
+    QMAKE_CXXFLAGS_WARN_ON += -Wno-sign-conversion
+
+    qhull_warn_shadow{
+        QMAKE_CXXFLAGS_WARN_ON += -Wshadow     # Shadowing occurs in Qt, e.g., nested foreach
+    }
+
+    qhull_warn_conversion{
+        QMAKE_CFLAGS_WARN_ON += -Wno-sign-conversion   # libqhullstatic has many size_t vs. int warnings
+        QMAKE_CFLAGS_WARN_ON += -Wconversion           # libqhullstatic has no workaround for bit-field conversions
+        QMAKE_CXXFLAGS_WARN_ON += -Wconversion         # Qt has conversion errors for qbitarray and qpalette
+    }
+
+    qhull_warn_all{
+        QMAKE_CFLAGS_WARN_ON += -Waddress -Warray-bounds -Wchar-subscripts -Wclobbered -Wcomment -Wempty-body
+        QMAKE_CFLAGS_WARN_ON += -Wformat -Wignored-qualifiers -Wimplicit-function-declaration -Wimplicit-int
+        QMAKE_CFLAGS_WARN_ON += -Wmain -Wmissing-braces -Wmissing-field-initializers -Wmissing-parameter-type
+        QMAKE_CFLAGS_WARN_ON += -Wnonnull -Wold-style-declaration -Woverride-init -Wparentheses
+        QMAKE_CFLAGS_WARN_ON += -Wpointer-sign -Wreturn-type -Wsequence-point -Wsign-compare
+        QMAKE_CFLAGS_WARN_ON += -Wsign-compare -Wstrict-aliasing -Wstrict-overflow=1 -Wswitch
+        QMAKE_CFLAGS_WARN_ON += -Wtrigraphs -Wtype-limits -Wuninitialized -Wuninitialized
+        QMAKE_CFLAGS_WARN_ON += -Wunknown-pragmas -Wunused-function -Wunused-label -Wunused-parameter
+        QMAKE_CFLAGS_WARN_ON += -Wunused-value -Wunused-variable -Wvolatile-register-var
+
+        QMAKE_CXXFLAGS_WARN_ON += -Waddress -Warray-bounds -Wc++0x-compat -Wchar-subscripts
+        QMAKE_CXXFLAGS_WARN_ON += -Wclobbered -Wcomment -Wempty-body -Wenum-compare
+        QMAKE_CXXFLAGS_WARN_ON += -Wformat -Wignored-qualifiers -Wmain -Wmissing-braces
+        QMAKE_CXXFLAGS_WARN_ON += -Wmissing-field-initializers -Wparentheses -Wreorder -Wreturn-type
+        QMAKE_CXXFLAGS_WARN_ON += -Wsequence-point -Wsign-compare -Wsign-compare -Wstrict-aliasing
+        QMAKE_CXXFLAGS_WARN_ON += -Wstrict-overflow=1 -Wswitch -Wtrigraphs -Wtype-limits
+        QMAKE_CXXFLAGS_WARN_ON += -Wuninitialized -Wunknown-pragmas -Wunused-function -Wunused-label
+        QMAKE_CXXFLAGS_WARN_ON += -Wunused-parameter -Wunused-value -Wunused-variable -Wvolatile-register-var
+    }
+}