Updated a few links

Author: joto

_libosmium_manual/02_dependencies.md

@@ -218,7 +218,7 @@ project OSM coordinates into spatial reference systems other than Web Mercator
 ### Doxygen
 
 The Libosmium API documentation can be built using
-[Doxygen](http://www.doxygen.nl/). Usually you do not need to do
+[Doxygen](https://www.doxygen.nl/). Usually you do not need to do
 this, because the API reference is available
 [online](https://docs.osmcode.org/libosmium/latest/). If you want to build it
 yourself, you need [Graphviz](https://www.graphviz.org/) in addition to Doxygen.

_libosmium_manual/03_building.md

@@ -162,7 +162,7 @@ Please report any issues you have and we might be able to solve them.
 ## Building the reference documentation
 
 To build the documentation you'll need
-[Doxygen](http://www.doxygen.nl/).
+[Doxygen](https://www.doxygen.nl/).
 
 After configuring with CMake as described above, call
 

osmcoastline/index.html

@@ -55,6 +55,6 @@ <h2>Download</h2>
 <h2>License</h2>
 
 <p>OSMCoastline is available under the <a
-href="https://www.gnu.org/licenses/gpl.html">GNU GENERAL PUBLIC LICENSE Version
+href="https://www.gnu.org/licenses/gpl-3.0.html">GNU GENERAL PUBLIC LICENSE Version
 3</a>.</p>
 

osmium-tool/index.html

@@ -72,6 +72,6 @@ <h2>Download</h2>
 <h2>License</h2>
 
 <p>The Osmium Tool is available under the <a
-href="https://www.gnu.org/licenses/gpl.html">GNU GENERAL PUBLIC LICENSE Version
+href="https://www.gnu.org/licenses/gpl-3.0.html">GNU GENERAL PUBLIC LICENSE Version
 3</a>.</p>