[Android] Split the AboutFragmentItem and InfoFragmentAdapter into their own class files.

It doesn't make sense conceptually to keep them within the AboutActivity, as they are entirely self-contained classes.
Add a namespace to DSPHost.

Gets rid of the "DSPHost_" prefix in function names.
Add more sound file extensions to FileMonitor's IsSoundFile.
Merge pull request #148 from lioncash/namespaces

Add a namespace to DSPHost.
Fix DSPTool.

Forgot to adjust the stubs.
Merge pull request #150 from lioncash/namespaces

Fix DSPTool compilation with the new namespace.
Rename assemble.cpp/.h and disassemble.cpp./.h to DSPAssembler.cpp/.h and DSPDisassembler.cpp/.h
MathUtil: fix IsQNAN()

The constants were one nibble too short and the lower 51 bits don't
actually have to be zero.
Interpreter: less duplicate code in float compares
Fix DSPTool string output for disassembly.

Would previously print that assembly had succeeded.
Merge pull request #151 from lioncash/rename-assemble-disassemble

Rename assemble.cpp/.h and disassemble.cpp./.h
Merge pull request #153 from lioncash/dsptool-string

Fix DSPTool string output for disassembly.
Merge pull request #152 from Tilka/float_stuff

Fix IsQNAN() and reduce code duplication
clang-modernize -loop-convert

and some manual adjustments
clang-modernize -add-override
clang-modernize -use-nullptr

and s/\bNULL\b/nullptr/g for *.cpp/h/mm files not compiled on my machine
Merge pull request #142 from Tilka/clang-modernize

Run clang-modernize and manually fix the result
Merge pull request #149 from lioncash/filemonitor-song-types

Add more sound file extensions to FileMonitor's IsSoundFile.
Merge pull request #145 from lioncash/split-about-activity

[Android] Split the AboutFragmentItem and InfoFragmentAdapter into their own class files.
[Android] Tidy up the dialog buttons that don't do anything.

All we want to do with these is dismiss the dialog. The same can be done by simply passing null.