glob-based syntax mapping

[sharkdp]

This PR changes the way --map-syntax works. The option now works like this:

--map-syntax <glob-pattern>:<syntax-name>

(this is a breaking change, users will have to adapt their config files)

This PR also adds a builtin database of syntax mappings to bat to handle cases such as:

• Glob-based lookups for paths:
  • /proc/cpuinfo => CpuInfo syntax
  • **/.ssh/config => SSHConfig
  • /etc/profile => Bash
  • *.h => C++ (I assume this is a better default than "Objective C")
• Files named build are no longer mapped to "NAnt Build File" (which should only match *.build files). Instead, we use the first-line detection mechanism on such files.

closes #592, closes #685
see also: #501

[cyqsimon]

Hi sharkdp, I'm working on making this system more extensible in #2747. I noticed that in c08d122 you made the match happen in reversed direction (so that mappings inserted later get matched first).

In the spirit of documenting the code behaviour as precisely as possible, I would like to ask you to clarify what your intentions were. My current hypothesis for why this was done is this allows rules inserted by the user at runtime to take precedence; is this correct?