Update Qwt to 6.1.

We also document how we got the source code and keep our modifications out of the Qwt directory.

Update Qwt to 6.1.
c96458cf · Bryant · 2e4ac6be · c96458cf · c96458cf · c96458cf
Commit c96458cf authored 10 years ago by Bryant
--- a/libs/qwt/qwt_text.cpp
+++ b/libs/qwt/qwt_text.cpp
--- a/libs/qwt/qwt_text.h
+++ b/libs/qwt/qwt_text.h
--- a/libs/qwt/qwt_text_engine.cpp
+++ b/libs/qwt/qwt_text_engine.cpp
--- a/libs/qwt/qwt_text_engine.h
+++ b/libs/qwt/qwt_text_engine.h
--- a/libs/qwt/qwt_text_label.cpp
+++ b/libs/qwt/qwt_text_label.cpp
--- a/libs/qwt/qwt_text_label.h
+++ b/libs/qwt/qwt_text_label.h
--- a/libs/qwt/qwt_thermo.cpp
+++ b/libs/qwt/qwt_thermo.cpp
--- a/libs/qwt/qwt_thermo.h
+++ b/libs/qwt/qwt_thermo.h
--- a/libs/qwt/qwt_transform.cpp
+++ b/libs/qwt/qwt_transform.cpp
--- a/libs/qwt/qwt_transform.h
+++ b/libs/qwt/qwt_transform.h
--- a/libs/qwt/qwt_wheel.cpp
+++ b/libs/qwt/qwt_wheel.cpp
--- a/libs/qwt/qwt_wheel.h
+++ b/libs/qwt/qwt_wheel.h
--- a/libs/qwt/qwt_widget_overlay.cpp
+++ b/libs/qwt/qwt_widget_overlay.cpp
--- a/libs/qwt/qwt_widget_overlay.h
+++ b/libs/qwt/qwt_widget_overlay.h