switch to sha256 checksums

* upgrade some broken packages
* correct some broken urls/checksums
* use secure urls where possible
* update PKGBUILD templates
* remove line-ending whitespace
* minor typos/fixes

Remaining md5sums either didn't download or
didn't pass checksum tests.

mingw-w64-python-matplotlib/PKGBUILD

@@ -31,9 +31,9 @@ makedepends=(
 source=("${_realname}-${pkgver}.tar.gz"::"https://github.com/matplotlib/matplotlib/archive/v${pkgver}.tar.gz"
         setupext.py.patch
         setup.py.patch)
-md5sums=('b22dc4962f36aab919a7125b3b35953b'
-         'cd1ef742fb22f91cfed3c36dd4a6f1e1'
-         'b5f64259a266ccc517586debb8c4e5c8')
+sha256sums=('64c9f7cce4075d05c2602108ee1795aa6455c2c1d8e4329c95c83465e3806887'
+            'ecaa1039d7527e31bbf175b23802123e843678bf0109fee4c76742d8eeee1fe0'
+            '17e4353062e165dfe54293e39d8924355a4a3c44f2ffee3739d7cc7bddc9c699')
 noextract=("${_realname}-${pkgver}.tar.gz")
 
 prepare() {