build: Replace Autotools with Meson

Quick rundown of benefits:

- Much faster:
  - Autotools (with autogen): 22 seconds
  - Meson: 7 seconds
  - Meson (with ccache): 2 seconds

- Simpler:
  - ~1000 lines smaller
  - Single simple language

- Potentially better Windows (Visual Studio) support

What is not done:

- Complete Windows support
- OSX support (easy)

Closes #2013
Closes #1937
Closes #1803

fedora-mingw64.ini

@@ -0,0 +1,17 @@
+; dnf install mingw64-{gtk,openssl}
+
+[binaries]
+c = '/usr/bin/x86_64-w64-mingw32-gcc'
+cpp = '/usr/bin/x86_64-w64-mingw32-g++'
+ar = '/usr/bin/x86_64-w64-mingw32-gcc-ar'
+strip = '/usr/bin/x86_64-w64-mingw32-strip'
+pkgconfig = '/usr/bin/x86_64-w64-mingw32-pkg-config'
+
+[properties]
+c_args = ['-DNTDDI_VERSION=NTDDI_WIN7', '-D_WIN32_WINNT=_WIN32_WINNT_WIN7']
+
+[host_machine]
+system = 'windows'
+cpu_family = 'x86_64'
+cpu = 'x86_64'
+endian = 'little'