Documentation update for issue #14

Added warning that C++ code must be used with double only, not with float.
Merge pull request #15 from hbf/fix-for-issue-14

Documentation update for issue #14
Fix for issue #14
Merge pull request #16 from hbf/fix-for-issue-14-2

Fix for issue #14
* Rename templated .C files to -inl.h (to prevent confusion);
* Complement (add missing) and reorder (alphabetize) includes;
Merge pull request #17 from bartvanandel/fix_filenames

Fix filenames: do not use .C for (essentially) templated header files
Added test_fromfile.cpp, from gist https://gist.github.com/hbf/7715996
Added test.
Added another test (infinite loop / segfault)
Tests now fail correctly, and check an expected result.

Note that the "infinite" tests don't yet have a known answer.
Merge branch 'mine' into primary

Conflicts:
	cpp/main/Subspan-inl.h
	cpp/main/Subspan.h
Removed redundant test
Bugfix, avoid infinite loop