EMI: Enable alpha blending for global alpha values of actors

This fixes the problem, that all actors with a global alpha
value < 1.0f were not drawn with the correct transparency.
EMI: Add specific detection for German Mac EMI
EMI: Add code for loading local.m4b from the german EFMI Installer file.
EMI: Add MD5 verification of the EFMI Installer file for german EMI
DOCS: Mention the necessary "EFMI Installer" file in Readme.md
EMI: Cache the entire contents of local.m4b to speed up the launch of the Mac version.

I did not remove the adding of local.m4b to SearchMan, as that for some reason blocked a few files from loading.
GRIM: SHADERS: Remove f literal suffix

Some Android shader compiler do not like it apparently
Merge pull request #1096 from chkr-private/alpha-fixes

EMI: Enable alpha blending for global alpha values of actors
AMIGAOS4: corrected cross building
AMIGAOS4: use upper case for target
GRIM/EMI: workaround for compilation error
MACOSX: added libiconv static lib
TINYGL: gl -> tgl rename
AMIGAOS4: replace package lha to zip
TINYGL: Rename glColor3fv to tglColor3fv

Linking TinyGL and OpenGL into the same binary could cause conflicts
because both have a glColor3fv function.
It is currently not used in ResidualVM, so it is safe to change this.
EMI: Add MD5 verification for the english mac installer thanks to clone2727
EMI: Make the MD5-check for german EMI use CD1s VoiceAll.m4b
GRIM: Enable screenshot saving on ES2
EMI: Reroute AttachActor/DetachActor to debug channel
GRAPHICS: Allow FrameBuffer to manage its own texture