add ':serial t' option to the system definition
re-enable checker texture RLE compression
replace texture type literal with concrete object data
add explicit generic for load-from-file method
fix byte order issue
1: Targa uses Intel endianness
2: Decrease byte numbers by 1
add file pointer setting with respect of Color Map and Image Id Targa fields
fix read-sequence misuse in load-uncompressed-targa function