Enable absolute imports, true division, & print()

These have no effect in Python 3.x, they are the default. Enabling them
in Python 2.x, enabling them in Python 2.x allows single source
compatiblity.

tools/csharp/__init__.py

@@ -21,4 +21,6 @@
 # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 # WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
-from csharp import exists, generate
+from __future__ import absolute_import, division, print_function
+
+from .csharp import exists, generate

tools/csharp/csharp.py

@@ -30,6 +30,8 @@
 #  This is an attempt to meld to two based initially on the Microsoft C# tool with amendmnets from the Mono
 #  tool.
 
+from __future__ import absolute_import, division, print_function
+
 import os.path
 import SCons.Builder
 import SCons.Node.FS

tools/csharp/mono.py

@@ -25,6 +25,8 @@
 
 #  This C# Tool for Mono taken from http://www.scons.org/wiki/CsharpBuilder.
 
+from __future__ import absolute_import, division, print_function
+
 import os.path
 import SCons.Builder
 import SCons.Node.FS

tools/scanreplace.py

@@ -1,3 +1,5 @@
+from __future__ import absolute_import, division, print_function
+
 from string import Template
 
 def replace_action(target, source, env):