PicrossEngine v1.1

Some bug fixes as well as a whole lot of general code enhancement.

Main additions:

• Upgraded hints shell command: grid hints can now be reset and otherwise manipulated in a bunch of ways
• More tests and comments

Bug fixes:

• XML deserializer now accepts XML grids with no content
• Text formatter now properly renders grids with no vertical or horizontal hints
• Text formatter now properly renders grids with hints of any character width
• Failproof exception handling
• Tests don't fail to compile anymore with MinGW
• Windows console now prints all characters properly

Planned for next release:

• Iterative solver
• Ease-of-life improvements to the CLI menus and grid modification shell

Attached files:

• PicrossEngine: Linux executable built with g++.
• PicrossEngine.exe: Windows executable built with g++ on a MinGW system.
• libstdc++-6.dll: a Windows DLL which the executable depends on (put in same folder).

Refer to build instructions on README.md in branch release-v1.1.