L10nConvertStr

Implemented L10nConvertStr as **only char* -> char* (type)**. this may cause problem when dealing with UCS2/UCS4/UTF16/UTF32 or other wide char encoding.
This may be used in other l10n functions, since it was designed to receive void* pointer.
Find **sizeof(size_t) is 4 (uint32_t?)** in Guided Fate Paradox. Thank @B1ackDaemon for testing.
Changed log content for this function. Also fixed many typos..
*Need windows sdk* for code page transformation on windows. *Need iconv* to build on Linux/Mac.
Original source for char to char codepage transformation is already tested using codeblocks and vs.
**Noticed l10n_conv_t is omitted in reference**, which may be replaced by iconv_t or simply other function. (Tip there are l10n_get_converter which very similar to iconv_t)
Modified .travis.yml to apt-get install libc6-dev and removed -liconv from CMakeFile.txt.
I've made some many mistakes and typo today, so the original commits are merged to one.(Sorry)